It's a dogmatic fact that Francis is Pope.

 “DOGMATIC FACTS. A dogmatic fact is one that has not been revealed, yet is so intimately connected with a doctrine of faith that without certain knowledge of the fact there can be no certain knowledge of the doctrine. For example, was the [First] Vatican Council truly ecumenical? Was Pius IX a legitimate pope? Was the election of Pius XI valid? Such questions must be decided with certainty before decrees issued by any council or pope can be accepted as infallibly true or binding on the Church. It is evident, then, that the Church must be infallible in judging of such facts, and since the Church is infallible in believing as well as in teaching, it follows that the practically unanimous consent of the bishops and faithful in accepting a council as ecumenical, or a Roman Pontiff as legitimately elected, gives absolute and infallible certainty of the fact.” (The Church of Christ, pp. 288, 289, 290)

It is evident, then, that the Church must be infallible in judging of such facts, and since the Church is infallible in believing as well as in teaching, it follows that the practically unanimous consent of the bishops and faithful in accepting … a Roman Pontiff as legitimately elected, gives absolute and infallible certainty of the fact.” (The Church of Christ, pp. 288, 289, 290)

This is what Cardinal Ratzinger taught as Prefect of the CDF in 1998:

http://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_1998_professio-fidei_en.html

With regard to those truths connected to revelation by historical necessity and which are to be held definitively, but are not able to be declared as divinely revealed, the following examples can be given: the legitimacy of the election of the Supreme Pontiff or of the celebration of an ecumenical council, the canonizations of saints (dogmatic facts), the declaration of Pope Leo XIII in the Apostolic Letter Apostolicae Curae on the invalidity of Anglican ordinations.