Are there any Windows users using ARTIQ-9? Is this possible yet via MSYS or has it not been released to Windows as of yet? Is ARTIQ-9 planned to be released on MSYS for Windows users when it is released?

Yes, presumably, yes, and yes. See the Installing page in the beta manual. ARTIQ-9 is the current beta version of ARTIQ (see Releases) and is packaged with the beta MSYS2 installer.

(If you already have an up-to-date MSYS2 ARTIQ and want to upgrade it to the beta, I suspect this would just require changing the server in pacman.conf and running a pacman -Syu but I'm not familiar enough with MSYS2 to be sure.)