Google makes single-digit billions in revenue from the Android App Store. While not explicitly broken out, the info is in their annual report [0], where "other revenues" are a bit over 10B USD (>10% of total revenue):
"Google other revenues consist primarily of revenues and sales from:
• Apps, in-app purchases, and digital content in the Google Play store;
• Hardware;
• Licensing-related revenue; and
• Service fees received for our Google Cloud offerings."
As an aside, the risks section is surprisingly interesting and honest. A recommended read.
[0] https://abc.xyz/investor/pdf/2016_google_annual_report.pdf