Not really - it’s no fixed expression for those; the only word there that can refer to mafia is “chefe” (boss, chief; “chefão” is its augmentative). But even then, “chefe” can be also used for company bosses, video game bosses, restaurant chefs etc., it doesn’t evoke mafia imagery at all unless you specify “chefe da máfia” (mafia boss) or similar.
I’ve seen a few people using “capo” (an Italianism) for that, but I don’t know how widespread this is.
Is Poderoso Chefão used to mean the leader of a gang/crime family in Portuguese?
Not really - it’s no fixed expression for those; the only word there that can refer to mafia is “chefe” (boss, chief; “chefão” is its augmentative). But even then, “chefe” can be also used for company bosses, video game bosses, restaurant chefs etc., it doesn’t evoke mafia imagery at all unless you specify “chefe da máfia” (mafia boss) or similar.
I’ve seen a few people using “capo” (an Italianism) for that, but I don’t know how widespread this is.