Let start with overall viewers, it topped around 610,000 here is a screenshot from the Twitch directory.
Click to enlarge picture.
With any large AAA Title, tons of streamers who usually do not play or stream world of warcraft all jumped in for the expansion launch. Here is a look at the top most streamers: 
Click to enlarge screenshot
Top streamers for launch include the following:
- sodapoppin - 84,750 viewers
- Asmongold - 60,350 viewers
- LIRIK - 31,170 viewers
- ZeratoR - 29,728 viewers
- TimTheTatman - 26,652 viewers
- Reckful - 23,506 viewers
- shroud - 21,415 viewers
- AtheneLIVE - 16,513 viewers
- Towelliee - 14,535 viewers
- ungespielt - 7,612 vierwers
It is always amazing to see the viewership numbers for game launches like this Twitch. You can also view how much of a viewership hit some of these non wow streamers take by switching over to it for the launch window. As of 7:30 PM, overall viewership numbers have gone down to around 495,991 Viewers. I guess the core viewers are now busy playing the game and stopped watching streams.
