My thinking would be that, especially for a game with Fortnite’s visual style, dynamic GI is sort of a near-pointless extravagance - there don’t appear to be a lot of scenarios in there that you can’t get a good enough result with dynamic shadows, good AO and fill lights. Also, as far as I’m aware they’ve stopped working on DFGI altogether, which wouldn’t make sense if Fortnite was going ahead with it.
Would be cool to get this confirmed/denied by someone on the FN team 