I would highly doubt they were larger within the time frame they started. Even though Twitch (Justin.tv) started back then, esports and watching video games were nowhere near as popular as they are today.

I would argue that Twitch has had a really strong role in making battle royale games popular -- they're extremely fun to watch in comparison to MOBAs which I'm starting to realize are fairly dull in the beginning but the anticipation of what happens mid-game to late game makes it exciting.