Almost never. But it does happen at lower levels because many players are too low skilled to recognize when they are irrevocably fucked and need to give up. So the ref is empowered to stop it if you are wailing haplessly.
I think it's only rare at a high level because submissions are rare at that level and verbal submissions even rarer.
But assuming that a verbal submission is used, a scream or yell is probably the majority of them. Only Americans seem to actually use the specific word "tap".
I know most of the Portuguese words for a BJJ context by now, but I don't know the word for tapping out -- mostly because I've never once heard a Brazilian actually say anything that could possibly translate to that. They all just yell out "Aiiiii!" when they are caught and that suffices.
I know how to say that you tapped somebody else, but I've literally never once heard a Brazilian tap out with a specific word in Portuguese.