The number of viewers on streams is a variable value. It depends on factors such as the popularity of the game, the time of the broadcast, seasonality. A strong decline in viewers can be observed when changing the subject. If a channel owner played Lost Ark for a few months and then switched to Final Fantasy XIV, you should expect a churn of subscribers.
Competition should be taken into account. If thousands of viewers come to any author to broadcast, it is not always right to choose his tactics. You can try another topic, in which there is less competition. You also need to take into account the time of the streams: it should not coincide with the time of the broadcasts of the top players. It is advisable to time the broadcasts to the hours of rest of users, when they have the opportunity to access their favorite content. All this will increase the number of subscribers.