If I can't skip ads, I wont watch twitch. Period. If refreshing the page doesn't bypass the ad, I'll simply close the tab.
Most of the time, I'll open a stream and watch 5-15 seconds of it just to get a sense of if I want to watch it. I might go through 6 or 7 channels before picking one to watch. If I have to sit through a 30 second ad just to immediately decide I don't want to watch that particular stream, then it's not worth using the site at all.