https://www.theverge.com/2017/12/12/16768198/twitch-echo-show-alexa-skill-streams

You can’t watch YouTube on an Echo Show anymore, but you can watch Twitch now, with the popular streaming website releasing an Alexa skill to play and navigate through Twitch content, via TechCrunch.

In addition to all the usual stuff you’d expect to be able to voice command Twitch to do — play a channel, discover new streamers, or watch a particular game — you’ll also be able to have Alexa notify you when your favorite channels start streaming, too.