ehhhhhhhhhhh
people who weren't really into gaming in the past are all up in fortnite now, male or female.
I have a feeling the bigger motivation is that its f2p.
Normally in shooters the best players dominate the game session you're in. Unless you're one of them, your experience is frustrating because mostly they're either killing you, if they're an opponent, or killing the people you were trying to kill, if the dominating player is your ally.
But in Battle Royale modes every game you're in will involve you dying only at most once.
For the dominant player they often don't die at all, a game lasts say 20 minutes and they might kill a dozen or more other players out of a hundred, then they're victorious. Hooray - they might do that two or even three times in a row. Amazing way to spend an hour.
But somebody like me - who isn't very good - doesn't last twenty minutes. They might win one or two fights, hide, get some cool stuff, but soon they're outmatched and... they die and can immediately start a different game. So for them an hour is maybe 15-20 games, each of them exciting and different, maybe they killed a few people, and the deaths, whilst not _fun_ per se, are over very quickly and you're straight into a different game.
In terms of why it would attract women. Everybody else being an anonymous enemy plus the "one death and you're gone" dissolves a lot of nasty abusive social stuff. Global chat would be pointless, you can't spawn camp people, you can't even tell if you see the same person twice usually because players don't have name tags.