I have my old doge wallet backup but there's no doge left in them. Do I still get clams?
That would depend. How old is your old doge back-up? If you DOGE back-up had coins in it when we did our dump some days ago; then yes, you could expect to find some CLAMS. If not, we are sorry.
That said, I suppose there is not harm in throwing the wallet in the client and checking

Haven't had doge in there in months, so maybe I'm out of luck.