This year’s Big House 6 managed to bring in a grand total of 73,687 viewers at its peak according to TwitchApps, which uses the Twitch API to calculate its numbers. Though perhaps some viewers saw larger numbers (I, for one, saw the number clock in at 77, 458 during grand finals) this is the amount apparently received from Twitch. However, it is possible that since TwitchApps does not poll the streams every second that it could have missed a sudden spike.
Last year’s Big House 5 saw 73k – 74k viewers which means viewership has remained steady (assuming the more conservative TwitchApps-provided figure).
Even so, BH6 boasted a whopping 1,563 entrants which is significantly higher than last year’s 1,320, and while viewership numbers may not have increased, the competitive scene continues to thrive and expand.
Edit: Special thanks to reddit user get_in_the_robot who pointed out that TwitchApps is not associated with Twitch like was previously claimed. He also pointed out that TwitchApps numbers might be averaged over time, giving lower peaks.