I'm getting the same error three time in a row, lauching the game, or into a match.
Error log looks like this :
I have been having the same types of crashes that it loads the game, finds opponent and changes music... then bam crash!
Disabled the anti virus didn't help
When I had a look at the error code of Access violation, I tried to run the game as admin (exec in Program Files (x86)\GalaxyClient\Games\Gwent (KTS))
and so far I have managed to get inside matches twice.
I hope its helpful!!