Your dad is in hell.
That's not exactly what the feedback online has been - but it's pretty close. Many Catholics wanted a by the book, strict catechetical-theological answer for the young boy. The little boy who asked the Pope about the eternal salvation of his father who died an atheist, has riled the enemies of the Holy Father once again. You see it expressed in com-boxes on social media and in the snarky headlines on at least one Catholic 'news' aggregate. Avoid those who are always judging and condemning.
"In the light of eternity the soul sees things as they really are." - S. Elizabeth of the Trinity.