Tez2 writes that soon (though the exact time is currently unknown), GTA 5 will be added to Xbox Game Pass for PCs for the first time. Previously, the game had been available in the paid subscription catalog multiple times, but only for consoles (most recently in the second half of 2023).
“The Five” along with GTA Online on board will be available through both the Xbox app and the Rockstar Games Launcher. However, crossplay will not be supported.
Source: gta.com.ua