It depends on the quality of the game, a few Construct 2 games made it to 500,000 or even 1,000,000 downloads, while some never become popular. I wouldn't recommend charging for the game itself, but adding ads or IAP's. Again, how much you make depends on your game. Most simple games don't get huge amounts of attention, but you never know. I don't have an exact answer on how much you can make though because i haven't published a game yet.