How would I answer my Protestant brother, using Scripture, that Pope Francis is not a false prophet or the Antichrist?
I’m not sure what the basis of your friend’s claim is, but for starters I would tell him that Pope Francis regularly affirms that Jesus is the Christ, the God-man, something Scripture tells us the Antichrist will not do (see 1 John 2:22, 2 John 1:7).
You can also tell him that, contrary to some opinions, Pope Francis has not changed any Church teaching and that the Holy Spirit will protect him and any other pope from doing so. In other words, the Antichrist will not be a pope. Ditto with a pope's being a false prophet.
Protestant claims that the Pope is the Antichrist are not new. For more on this subject, see our tract “The Antichrist,” as well as a related article by Jimmy Akin.