Most companies don't reveal the exact amount of revenue a single game makes them in a specific time period and sometimes not at all. As a result, keep in mind that all these figures are just estimates based on the data available to the public. Some of the figures may lack accuracy however the top 2 (Genshin and Fortnite) are relatively reliable.

Regarding Genshin Impacts revenue breakdown:
- 2.1 billion is the confirmed amount for mobile only revenue (not including PlayStation, PC, and 3rd party android appstores).
- The 3.7 billion figure is the high-end estimate but is quite likely the actual amount earned based on the data available.
- The high-end figure assumes that mobile revenue (excluding 3rd party android in China) accounts for roughly 60% of Genshin Impacts total revenue. That leaves an additional 40% (roughly 1.4 billion) of revenue from Playstation, PC and 3rd party Android.
- The low-end figure is much more conservative and assumes mobile revenue accounts for 90% of the games revenue.
- To understand where these estimates come from you can refer to the bilibi post linked below. 

Regarding the Fortnite estimate:
- The low-end figure was confirmed in the court documents that were released as part of EPIC's legal battle with Apple inc.
- The high-end estimate is based on available data but was not confirmed in the court documents as those documents only list Fortnite's earnings for the year of 2018 which does not include the 6 months following its release in 2017.


Sources:

- Genshin
https://www.bilibili.com/read/cv12883378
https://sensortower.com/blog/genshin-impact-mobile-two-billion-revenue
https://sensortower.com/blog/top-mobile-games-by-worldwide-revenue-september-2021

- Fortnite
https://www.businessofapps.com/data/fortnite-statistics/
https://s3.documentcloud.org/documents/20696836/epic-apple-trial-epic-games-exhibit.pdf

- GTA V
https://www.statista.com/statistics/1097608/gta-v-unit-sales-worldwide/
https://www.tweaktown.com/news/80898/gta-sales-figures-145m-at-least-10m-year-since-2013/index.html

- COD: MW
https://investor.activision.com/news-releases/news-release-details/call-duty-modern-warfare-1-most-played-call-duty-multiplayer
https://en.wikipedia.org/wiki/Call_of_Duty:_Modern_Warfare_(2019_video_game)

- Animal Crossing
https://www.nintendo.co.jp/ir/pdf/2021/210201e.pdf#page=3
https://www.nintendo.co.jp/ir/en/finance/software/index.html
https://en.wikipedia.org/wiki/Animal_Crossing:_New_Horizons#Sales

- RDR2
https://venturebeat.com/2019/02/06/red-dead-redemption-2-gallops-to-23-million-copies-in-a-quarter-stock-falls-13/
https://www.gamespot.com/articles/red-dead-redemption-2-sales-surge-as-gta-online-sets-more-records/1100-6484162/
https://www.gamesindustry.biz/articles/2021-02-08-nba-2k-gta-catalog-titles-drive-take-twos-holiday-quarter
https://en.wikipedia.org/wiki/Red_Dead_Redemption_2#Sales

- Monster Strike
https://www.dfcint.com/monster-strike-revenue-soars/
https://en.wikipedia.org/wiki/Monster_Strike#Commercial_performance
https://www.gamesindustry.biz/articles/2015-05-13-monster-strike-drives-900-per-cent-profit-growth-for-mixi
https://toyokeizai.net/articles/-/116373

- Candy Crush
https://www.businessinsider.com/kingcom-generates--1-billion-from-candy-crush-2014-2?IR=T
https://en.wikipedia.org/wiki/2013_in_video_games

-Puzzle & Dragons
https://www.pocketgamer.biz/asia/news/57076/its-official-puzzle-and-dragons-is-the-first-mobile-game-to-1-billion-in-revenue/
https://www.gamesindustry.biz/articles/2018-07-31-gungho-shares-slump-on-decline-of-puzzle-and-dragons

- PUBG
https://web.archive.org/web/20190121010757/https://www.superdataresearch.com/market-data/market-brief-year-in-review/
https://variety.com/2019/gaming/news/pubg-mobile-passes-fortnite-ios-1203142525/
https://en.wikipedia.org/wiki/2018_in_video_games#cite_note-24

- Lineage M and Pokemon Go
https://sensortower.com/blog/genshin-impact-mobile-two-billion-revenue