Right now we're #24, with 34,320 votes. Available data is limited but #15 for example has 43,472 votes. Its clear we need to get at least 20k more votes to get in the top 10, but on the other hand it might not be needed.
Valve refrains from putting a specific target (rank, votes) on being Greenlit, and in fact last time they greenlit some games, a couple of them were lower ranked than us.
What probably matters is:
-how special you are (yay?)
-Mac/Linux support (yay!)
-how close you are to release
-whether you can release via Early Access (yay!)
According to our limited info ... it can take quite a lot of time. You can read Receiver's Greenlight saga here: http://blog.wolfire.com/2013/04/Receive ... ht-Journey