Epic said this figure is for "all of Fortnite," so it sounds like it covers the paid base game and the free-to-play Battle Royale experience.
"We just passed 20 million players across all of Fortnite since launch! Thanks to everyone who keeps making the community and the game awesome!" Epic said on Twitter. The developer did not provide a breakdown between the base Fortnite game and Battle Royale, but we'd imagine the free-to-play Battle Royale has more players.
Additionally, the new Battle Royale patch adds the Season Shop, which is where Battle Royale players can purchase items like gliders, outfits, and weapons.