It’s possible to request a full list of a broadcaster’s subscribers (https://dev.twitch.tv/docs/api/reference#get-broadcaster-subscriptions) but this does not include sub tenure. The CSV download from https://dashboard.twitch.tv/channel-analytics does include sub tenure, but does not include user IDs, making historical data unreliable. (It’s also not easy to access programmatically.) Please can there be a way to find out sub tenures via the API?
No, but there is a uservoice open for it
Ah well. Guess we’re waiting for the feature to be added. Voted and commented on the uservoice. Hopefully it’s an easy one to add…