No doubt. Most producers who were writers at one point, like Tim Kring and Fey, seem to support the WGA. Plus, keep in mind, even if she wasn’t a member of the WGA, Fey couldn’t write any new episodes according to union rules lest she face penalty and/or blackballing in the industry. When they go to film new eps, they’re not even allowed last minute re-writes for scripts that were already in the can when the strike hit. Actors aren’t allowed to change their dialogue either on set.
What’s unclear is where this falls with the animation. Originally the strike rules didn’t cover animation because they’re not covered by the WGA, but in a recent Brian K. Vaughan interview it seems that may have changed.