These are rumours, but they do come from a source with an interesting track record. A user who has previously leaked information on The Mandalorian skins in Fortnite, has now leaked new Halo skins for Fortnite. A known dataminer going by the name Mang0e_ has tracked down the source on 4chan.
Yesterday PlayStation teased the arrival of Kratos from God of War to Fortnite. It seems every platform is receiving a skin, but nothing has been announced yet.