Twitch doesn’t provide access to much historical information, the closest you can get is by checking the streamers VoDs https://dev.twitch.tv/docs/api/reference#get-videos but that may be completely inaccurate as the streamers last broadcast may not have been chosen to be recorded, or was recorded and since expired.
Realistically the only way to know with any real accuracy is if you poll the API, or use Webhooks, for the streams endpoint with that broadcaster, and then store the results yourself. If you want to do this for a large number of channels it’s not something that will scale or be viable for you.