It has been VGC who has echoed this news when checking the figure through the total user counter that can be found in the hall of Fame classification table of the game. The last figure that has marked at the time of publishing its own news has been 20,012,405 players in total, a number they have achieved after seven months after its launch.
At that time (before Halo Infinite came out, with the handicap that his online mode is f2p), Forza Horizon 5 became the largest launch of Microsoft after getting 4.5 million users in just one day. It must also be account that at least one million of them had to go through the box at some point (beyond Game Pass) because before it left, it already had that number of users for which they made the premium package.
To achieve these figures, it has also helped the constant content that Playground Games has been adding, where we cannot pass the compatibility for sign language that added three months ago, something that included the North American ASL and the British BSL.
Forza Horizon 5 is available for Xbox Series X and S , Xbox One and PC , through Steam and Microsoft Store. You can play in all systems, also in Xbox Cloud Gaming, with a Game Pass subscription.