Don't old folks call it supper?
I'm not aware of it being generational, but it is very regional. In some places, it's one is predominant and the other is rarely used. In others places, they're interchangeable. For some regions, the two words have somewhat more distinct meanings - one is a more formal meal than the other, or something like that, but I wouldn't know which is which. If you haven't taken this, it's an interesting way to waste a few minutes -
NYT Dialect Quiz Map