well, there isn't a huge difference, "and so on" means continuing in the same way, just like (and so forth, or etc) and "what have you" means "whatever you wish.., what remains and need not to be mentioned.." so it's used to borrow an example already used, ex: a room full of chairs, lamps, radios, and what have you.

Thank you so much.

There is not too much of a difference in most situations. It depends on context, however, what they really mean. To me, "what have you" is very casual and would be something I would only expect to hear in spoken English... not written English. "And so on..." has a sense of continuing and the continuing is somewhat irrelevant. If you post some example sentences you might get a better answer. :)