Esports are rising, and at the moment their publicity stays in the social media. Football doesn´t need publicity, because you see it everyday in the news and in the TV, but Esports at the moment has to make noise so in that way they will grew.
The way this industry is moving nowadays is with the content creators. In YouTube there are a lot of gaming content, and these influencers are in the charge of promoting Esports (going to tournaments, or like Ibai, joining to a team such as G2).
A few months ago, we lived one the most important tournaments of Esports. Youtubers from every part of the world joined for a benefit tournament. This campaign was not promoted by the Esports league, it was promoted by Youtubers (this had a lot of repercussion, because each participant has more than a million subscriber). That is why they don´t really need to do marketing on their social media, because their marketing is in an indirect way gaming content creators. The target public of Esports are the followers of a gaming channel in YouTube because those users likes watching video games.
So yes, the Social Media they use more (in an indirect way, and for free) is YouTube and Twitch, and their marketing workers are Youtubers and streamers... and people like us, writing blogs; so in conclusion content creators.