It really depends what TGP and how much traffic the TGP sends out to galls.
What do you mean by Top 10? The Sextracker Top?
Let's say you get a top spot at a decent size TGP, and you get about 20k clicks to your gallery daily. If your CTR is 5%, you will get 1000 click-throughs to your tour. Assuming you are converting at 1:300 or so, you will get roughly 3 sales a day - 90 sales a month.
VERY rough estimate. It all depends on....well....everything.
Elaborate and I will be able to give you a better estimate.