https://www.pcgamer.com/fortnite-earned-dollar100-million-on-ios-in-just-90-days/

The iOS version of Fortnite turned out to be a lot better than we expected, even before it was released to the public at large. It is also, according to analysis firm Sensor Tower, a massive financial success for Epic. The site said that the game needed just 90 days to pull in $100 million in revenues, making it one of the most successful mobile games to come along in years—and putting it far ahead of PUBG. 

Fortnite lagged behind Clash Royale, which earned $1.2 billion in 2017, in the time it took to hit the $100 million mark, but achieved it much more quickly than other top-selling games. (Both figures exclude revenues from China.) A direct comparison to PUBG isn't available because it had only been monetizing for 60 days at the time of the report, but Sensor Tower estimated that it rang up a relatively paltry $5.2 million in revenues over that period. It also pointed out that for the first two weeks of that 90-day stretch, Fortnite was only available via invitation—basically, it was a closed beta, so incoming revenues would have been much lower than normal.