This is self-published research by a think-tank, not a peer reviewed scholarly publication; also, the actual paper for this finding doesn't yet seem to be available, just summaries by news organizations. This article does link to some older papers by them, which go into very little detail on methodology.
As such, it's really hard to say what kind of abuse they are talking about; slut shaming and rape threats, while both awful, can be quite different. Also, I am curious about how they accurately determine gender of Twitter users; there are many fake accounts on Twitter, and I don't believe Twitter even reports gender identity of users.