Streaming platform Twitch is well on the way to surpassing 40 million users in the US alone by 2021. 

That's according to eMarketer, which took a look at the current growth rate of Twitch's numbers. The company also estimates that Twitch will see around 37.5 million users in the US in 2020.

Twitch's US viewers in 2019 hit 32.9 million and given its current pace, that number will rise by 14.3 per cent. In order to count as a viewer, a user must watch a Twitch stream at least once a month.

"Twitch is by far the largest platform for streaming video game content, well ahead of YouTube, Mixer and Facebook Gaming," said eMarketer forecasting analyst Peter Vahle.

"As the pioneer in this space, Twitch has built a loyal and engaged audience by allowing viewers to directly interact with their favorite streamers."

Shapeshifting market 

While Twitch is still a safe leader in the streaming space, it's seeing solid competition from growth on other platforms. In Q4, Facebook dramatically increased its share of the market, leaping from 3.1 per cent in 2018 to 8.5 per cent in 2019. YouTube Gaming also holds a solid quarter.

Twitch's top creators are also in a state of flux; a few of the platform's biggest streamers jumped ship in the last half of 2019. The trend seemed to be sparked by the platform's biggest streamer - Tyler 'Ninja' Blevins - making the move to Microsoft's Mixer back in August last year. 

A lot of Twitch's growth is also attributed to the increasing popularity of esports events. Week by week, the platform is dominated by channels dedicated to professional esports coverage bringing in millions of views a day.