Contact streamers or their management groups and offer them access to your game to play, of even just make them aware you exist (some will just buy the game (if available) to avoid viewers thinking SPONSORED STREAM MUST SAY GOOD THINGS for example). Most have business emails publicly displayed on their profile (twitch/Twitter) best not to contact a streamer whilst they are live. Since whilst live they are busy streaming.
Some GameDevs run Twitch Accounts as they do dev streams, or promotional streamers on their channel, but you don’t need one.