I'm not sure the Vatican's revenue but I suppose a lot comes from the Vatican Bank and returns on their massive assets. Most of their charitable work comes from $2+ billion from the US Govt.
If you've seen Vatileaks on PBS, you know how frighteningly corrupt it is. The Pope's personal butler was a whistleblower, went to the media and then was arrested for possession of "classified" material. Sentenced to 18 months in prison but he instead served it in the Vatican. Then the Pope pardoned him.