Supercell, like most big mobile gaming companies, make their money on in-app purchases. Someone leaked SC's internal dashboard 2 years ago [1]. At the time they were making $5M a day in rev just in CoC. You can get App Annie estimates of revenue for other companies pretty easily, but last I checked SC was able to dramatically increase LTV of users over the years so this has likely grown.

[1] https://recodetech.files.wordpress.com/2014/02/supercell-hac...