While we're making unfounded statements based on our own anecdotal experiences: can't speak for Gnome users (very few in my circle), but for KDE and tiling window manager users, it's a lot of X11. Hard to say exactly, but would put it at ≥50% X11.
Personally I have given up with wayland as in years ago. There will always be something I should not have wanted to do in the first place while using wayland. I would rather use x11 and have much better control.
https://qa.debian.org/popcon-graph.php?packages=x11-common+g...
https://pkgstats.archlinux.de/compare/packages#packages=gnom...
You could try comparing xserver-xorg-core instead, but even then that'll only show you the number of submitters who have it installed, not the number that actually use it. The usual way to get a graphical desktop in Debian (task-desktop) pulls in both Wayland and Xorg, but uses the former by default.
The best estimate would be something like the number of xserver-xorg-core installs less the number of xwayland installs.
Using that method, it looks like there are roughly twice as many GNOME users as pure Xorg users.