The player count for Fortnite may have been revealed via Sony's 'My PS4 Life' tool. Released to celebrate five years of the PS4's existence, Sony emailed PS4 players to try it out. One of the points of data it covers is the number of PS4 players to obtain a trophy. When used along with the percentage of players, it becomes easy to deduce a total player player base. And according to the math done on Gamstat, Fortnite has at least 16.2 million players in Europe and Australia alone. Since Fortnite's battle royale mode did not ship with PS4 trophy support (or Xbox One achievements for that matter), Fortnite appears to have 16.2 million players for its Save the World version.
Considering this Fortnite[1] player count data is just for two regions, it's staggering even when you factor in PS4 account sharing, game sharing, and scenarios where a single PS4 is used by multiple accounts. How this works is, if the My PS4 Life tool says[2] 33,764 players obtained the 'Photo Bomber' trophy in Fallout 76, you can check that trophy's rarity on PSN, which is 8.3 percent. This is enough to reach an estimate of 406,795 PS4 users have played Fallout 76.
And while the data is as recent as December 4, it appears that Grand Theft Auto V[3] has sold at least 51.7 million units on the PS4. Meanwhile, FIFA 16, 17, and 18 have sold over 90 million and Overwatch[4] at least 10.2 million, while Call of Duty: Black Ops 4[5] has had 9.23 million at the very least.
It will be interesting to see how Sony fixes this data snafu. Traditionally, most video game publishers and developers are secretive...