I don't watch many streams live, but I do watch segments on YouTube. I don't play Hearthstone anymore, but I still like to watch others play. I don't think I care about gender, but I watch a lot more videos from male streamers than female, and I've wondered for a while why that is. I think there's a number of factors.
First, there are just a lot more male players that are prevalent. More of them play in tournaments, more of them partner with Blizzard, and more of them are favored by YouTube's algorithms. I have no idea if more men play the game, overall, though. Second, of the streamers I do follow (Trump, Kripp, RegisKillbin, Alliestraza, Hafu, etc.) there are more men who are consistently putting out a video every single day. I don't know why that is, though.
Third, and this especially applies to the rare occasion that I watch a stream live on Twitch, is that I really like it when the streamer makes constant commentary on their strategy and the state of the game. When I have looked through random streams it's always been easier to find guys who are actively commenting on the game, and I've wondered why that is, but I've recently become aware of a factor that surprised me. Twitch chat tends to become vocally upset when female streamers talk too much, and talk with too much authority about the game they're playing. Despite the claims that viewers don't want an "e-thot" who just looks good and doesn't know about games, it's pretty clear there are a lot of vocal assholes who don't want female streamers to be experts, either. This makes it much harder for female streamers to engage with their audience in the same way that male streamers can.
Twitch chat, in general, is one of the reasons I don't watch much on Twitch. For any popular streamer, chat becomes extremely toxic, but even for valuable chat interactions, a lot of streamers have no freaking clue how to handle commenting about they've just read in chat. Streamers need to stop assuming that their viewers are going to be able to know what chat comment they're replying to. Like public speakers responding to an audience comment/question, streamers need to learn how to repeat/rephrase what they're replying to, so that their audience only ever has to know what the person "on stage" has said.
As with so many things in life, I find it frustrating that the mass of consumers who want a significantly different product than I do, end up dictating what is readily available for me.