Firebase Auth get additional user info (age, gender) – Twitter API

Unfortunately, Firebase doesn’t have any built-in functionality to get the user’s gender/birthdate upon successful login. You would have to retrieve these data from each of the providers yourself.

Here is how you might get the user’s gender from Google using Google People API

public class SignInActivity extends AppCompatActivity implements
        GoogleApiClient.ConnectionCallbacks,
        GoogleApiClient.OnConnectionFailedListener,
        View.OnClickListener {
    private static final int RC_SIGN_IN = 9001;

    private GoogleApiClient mGoogleApiClient;

    private FirebaseAuth mAuth;
    private FirebaseAuth.AuthStateListener mAuthListener;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_google_sign_in);

        // We can only get basic information using FirebaseAuth
        mAuth = FirebaseAuth.getInstance();
        mAuthListener = new FirebaseAuth.AuthStateListener() {
            @Override
            public void onAuthStateChanged(@NonNull FirebaseAuth firebaseAuth) {
                FirebaseUser user = firebaseAuth.getCurrentUser();
                if (user != null) {
                    // User is signed in to Firebase, but we can only get 
                    // basic info like name, email, and profile photo url
                    String name = user.getDisplayName();
                    String email = user.getEmail();
                    Uri photoUrl = user.getPhotoUrl();

                    // Even a user's provider-specific profile information
                    // only reveals basic information
                    for (UserInfo profile : user.getProviderData()) {
                        // Id of the provider (ex: google.com)
                        String providerId = profile.getProviderId();
                        // UID specific to the provider
                        String profileUid = profile.getUid();
                        // Name, email address, and profile photo Url
                        String profileDisplayName = profile.getDisplayName();
                        String profileEmail = profile.getEmail();
                        Uri profilePhotoUrl = profile.getPhotoUrl();
                    }
                } else {
                    // User is signed out of Firebase
                }
            }
        };

        // Google sign-in button listener
        findViewById(R.id.google_sign_in_button).setOnClickListener(this);

        // Configure GoogleSignInOptions
        GoogleSignInOptions gso = new GoogleSignInOptions.Builder(GoogleSignInOptions.DEFAULT_SIGN_IN)
                .requestIdToken(getString(R.string.server_client_id))
                .requestServerAuthCode(getString(R.string.server_client_id))
                .requestEmail()
                .requestScopes(new Scope(PeopleScopes.USERINFO_PROFILE))
                .build();

        // Build a GoogleApiClient with access to the Google Sign-In API and the
        // options specified by gso.
        mGoogleApiClient = new GoogleApiClient.Builder(this)
                .enableAutoManage(this, this)
                .addOnConnectionFailedListener(this)
                .addConnectionCallbacks(this)
                .addApi(Auth.GOOGLE_SIGN_IN_API, gso)
                .build();
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.google_sign_in_button:
                signIn();
                break;
        }
    }

    private void signIn() {
        Intent signInIntent = Auth.GoogleSignInApi.getSignInIntent(mGoogleApiClient);
        startActivityForResult(signInIntent, RC_SIGN_IN);
    }

    @Override
    public void onActivityResult(int requestCode, int resultCode, Intent data) {
        super.onActivityResult(requestCode, resultCode, data);

        // Result returned from launching the Intent from GoogleSignInApi.getSignInIntent(...);
        if (requestCode == RC_SIGN_IN) {
            GoogleSignInResult result = Auth.GoogleSignInApi.getSignInResultFromIntent(data);
            if (result.isSuccess()) {
                // Signed in successfully
                GoogleSignInAccount acct = result.getSignInAccount();

                // execute AsyncTask to get gender from Google People API
                new GetGendersTask().execute(acct);

                // Google Sign In was successful, authenticate with Firebase
                firebaseAuthWithGoogle(acct);
            }
        }
    }

    class GetGendersTask extends AsyncTask<GoogleSignInAccount, Void, List<Gender>> {
        @Override
        protected List<Gender> doInBackground(GoogleSignInAccount... googleSignInAccounts) {
            List<Gender> genderList = new ArrayList<>();
            try {
                HttpTransport httpTransport = new NetHttpTransport();
                JacksonFactory jsonFactory = JacksonFactory.getDefaultInstance();

                //Redirect URL for web based applications.
                // Can be empty too.
                String redirectUrl = "urn:ietf:wg:oauth:2.0:oob";

                // Exchange auth code for access token
                GoogleTokenResponse tokenResponse = new GoogleAuthorizationCodeTokenRequest(
                        httpTransport,
                        jsonFactory,
                        getApplicationContext().getString(R.string.server_client_id),
                        getApplicationContext().getString(R.string.server_client_secret),
                        googleSignInAccounts[0].getServerAuthCode(),
                        redirectUrl
                ).execute();

                GoogleCredential credential = new GoogleCredential.Builder()
                        .setClientSecrets(
                            getApplicationContext().getString(R.string.server_client_id), 
                            getApplicationContext().getString(R.string.server_client_secret)
                        )
                        .setTransport(httpTransport)
                        .setJsonFactory(jsonFactory)
                        .build();

                credential.setFromTokenResponse(tokenResponse);

                People peopleService = new People.Builder(httpTransport, jsonFactory, credential)
                        .setApplicationName("My Application Name")
                        .build();

                // Get the user's profile
                Person profile = peopleService.people().get("people/me").execute();
                genderList.addAll(profile.getGenders());
            }
            catch (IOException e) {
                e.printStackTrace();
            }
            return genderList;
        }

        @Override
        protected void onPostExecute(List<Gender> genders) {
            super.onPostExecute(genders);
            // iterate through the list of Genders to
            // get the gender value (male, female, other)
            for (Gender gender : genders) {
                String genderValue = gender.getValue();
            }
        }
    }
}

You can find more information on Accessing Google APIs