Sometimes people remark that their priests never preach about the Four Last Things: Death, Judgment, Heaven and Hell.
Today during his Angelus address, a reflection on November and the Christian meaning of death, the Holy Father stated in very certain terms that someone who dies in the state of mortal sin excludes himself from heaven. Italian with my translation:
"Chi muore in stato di peccato mortale senza pentimento, chiuso nella orgoliosa rifuita dell’amore di Dio, si autoesclude dal regno della vita. … One who dies in the state of mortal sin without penitence, closed up within the proud refusal of the love of God, excludes himself from the kingdom of life."