I hope you don't think only a multi billion dollar companies count as success. The point is: a lot of poor people start businesses all the time and a lot of them end up successful.
I would not count working 12+ hours per day 7 days a week, while barely making each months rent as success. As far as I can tell that's the reality for most non-franchise stores, small restaurants, etc.
I don't know. A lot more than there are companies like Apple or Google. Don't you see how many small businesses are around you when walking down a random street. Anyway why does it even matter? If only 49% of them succeeded which is less than majority, would that mean poor people cannot become successful entrepreneurs?