Hello Max,
I'd say still a fair amount still plays. Like you, I've been trying to undust my skills a bit.
The exact numbers you'd have to ask someone else, but during my evenings, there are about 50-60 players online.
Make sure to download the 1.02 patch and the supported mappacks:
Patch: https://www.gamerepl...howtopic=889347
Mappacks: https://www.gamerepl...howtopic=992383
Were you a 1v1 or 2v2 player btw?
Hope this helps,
Have a nice day.