That's a movie sequel to one of the most popular RPG's of all time, Final Fantasy VII.
As such, being familiar with FFVII will definitely help. I haven't seen it or the preview yet, so I don't know if it's required.
Regarding the game franchise, even though they are numbered like sequels, the games aren't true 'sequels', with the exception of FFX and FFX-2. They share some commonalities [some monsters, some gameplay concepts, airship, Cid, spells, summons, etc], but AFAIK, it's really not necessary to play any of them to 'know what's going on' in other games [again, except for FFX and FFX-2, although even that isn't really 'necessary', except for the overriding plot point of 'who's this guy']. And for the last couple iterations, they have tweaked major portions of the game [either the way the game plays, or the way the characters get skills, or the way combat plays out] so they're not just rehashing the whole thing.