How much money?

How much money could you get per day if you play guitar on a city street corner?

There is absolutely no way to tell for sure. I guess it depends on the generosity of the people you happen to encounter that day. Also it may be against zoning laws to do that, so you may be asked to leave before you make anything. Maybe ask a small cafe or something if you can play in their shop for tips. You never know they may like it so much that they hire you to play a few nights a week. Good luck.

not much. and anyway, you can't just go on any street corner and start playing. you have to get a permit

I would say dont do it, first, you'll look crazy, like a crazy homeless person, and you'll probably end up making good friends with hobos and you'll see what the hobo life truely is for the first time and it will open your mind and change your life and truely be free from what you know as society for the first time in your life, you wont want to do anything youll just be content strummin your guitar on the corner with your hobo band and you'll go on hobo tours all across the nations big homeless citys. to answer your question I dont think hobos pay other hobos for traveling music(maybe with a half piece of corn bread?) I think hobo music is something as free and as wild as the hobos themselves or so I've heard.