Fortnite has been out for iOS devices since March 2018 and since then has generated over $455M through over 82.6M downloads. December 2018 was the iOS version's biggest month to date with Epic bringing home $69M, on average about $1.6M per day on iOS alone.
By comparison, Fortnite's biggest competitor on iOS, PlayerUnknown's Battlegrounds, has generated about $100M throughout 2018.
December’s revenue marked a month-over-month increase of 83 percent compared to November and was 16 percent higher than its previous best month of July when the game grossed an estimated $59.3 million. All told, the game grossed more than $455 million during 2018 on Apple’s App Store, on top of the revenue it took in on Android after its publisher opted to make an end run around Google Play.