GTA IV managed to generated $2 billion in worldwide sales in its heyday, but it doesn't hold a candle to GTA V's juggernaut earnings.
According to ex-Rockstar producer Franceska Bucci, Grand Theft Auto IV made over $2 billion in lifetime sales revenues. The current data shows GTA IV managed to sell 28 million copies since 2008. These are massive figures compared to most games, but Grand Theft Auto V absolutely crushes its forebear.
In comparison, GTA V has now sold a monumental 135 million copies since 2013. GTA V has the added benefit of releasing across two whole generations of consoles--and is about to re-release on PS5 and Xbox Series X/S too. GTA V's revenues are also significantly higher thanks to GTA Online; in 2019 alone, GTA V and GTA Online generated over $500 million, or roughly 1/4th of GTA IV's total lifetime earnings. GTA Online managed to break $1 billion in earnings way back in 2017 solely from microtransaction purchases.
Rockstar is set to expand these earnings even further with its new GTA plan. First, GTA V will get re-released on next-gen hardware with high-end optimizations and performance. Secondly, Grand Theft Auto Online will soon be a standalone game similar to how Red Dead Online is now sold separately for $19.99.
The developer is also working on Grand Theft Auto VI, which may or may not be set in a drug-fueled South America, while also tying Los Santos, California and Vice City, Miami together in a cartel-wrapped package.