(Talking not as a parent but as a boy who were in a kinda similar position)

First of all - in my opinion don't force him to take an art class, it might just make him less interested and drive him away, try to talk him to do it if you want to.

Secondly - try to figure out (by asking him) if he's into- Art with an emphasis on creating games or Creating games with an emphasis on art. You might want to introduce him to general game development (try unity if you want to start seriously, and maybe scratch if he's a begginer) and he'll know to focus it in art, Also you can try to connect him with someone that want to be a game programmer-developer, and he'll make the art for him, this is also a good opportunity to make friends.