I’ve search high and low and the best I can find is this site below. Interestingly it shows more people play male characters, and druids now outnumber paladins. And blood elves make up 20% of all characters. 
As for the topic title, it says the imbalance is now 64/36 in favor of the Horde. I remember in legion reading 55/45. Has it really gotten that bad?
I’d be interested to see if anyone has a more reliable set of numbers out there. I’d love to know.
No. Blizz made it impossible to gather census data so almost all the data you find is an estimate
The best you can do is look at Raider.io completion data to compare completion %s
I assume the stuff in this Tweet isn’t made up, but I don’t know where it came from.
Thanks. This is great data. Though things are looking bleak for team blue.
It does seem like a roughly 65/35 split is where we are at.
I got the Tweet link from this thread, which is talking about the same issue in regards to cross faction play:
https://us.forums.blizzard.com/en/wow/t/mr-hazzikostas-tear-down-this-wall/1098679
Wow 99.72% horde on 1 server