There is no limit on how many members can be added to a channel with Stream Chat. However, there are some limitations to be aware of.
1. Only the first 1,000 members receive push notifications
2. The first 1,000 members can have an unread count for the channel
Some channels come pre-built with "open" permissions, such as Livestream type channels, which do not require membership to view/interact with. You can add thousands of watchers to these channels, but be aware that we throttle some features and events after 100 watchers