These are only my rough estimates and not real data ;)
Sweden vs. Italy
Started with 18k viewers out of which 12k were on main stream (2k more on youtube) but by the half time it grew to 25k and 18k on main stream (5k more on youtube) and by the end it was just shy of 30k and 20k on the main stream, 2nd biggest stream was korea with 2.2k and 3rd france with 1.5k (a lot less then in shanghay)
Australia vs. Portugal
it started with just under 30k and ended little bit over 30k, but number of korean viewers was growing and number of french (and eu in general) viewers decreased
Finland vs. Spain
Already before it started number of viewers started growing and not before long into match it stabiliesed at nearly 40k with 30k from the main stream and 5k on Korean and 2.4k on chinese stream ( http://i.imgur.com/iVCpwgq.jpg)
Japan vs. Vietnam
it was not the most hyped match of the day but i was still curious to see japan play (akm in so many teams! kappa) and to my suprise viewership havent sroped after finlandspain match ended, and just slowly decreased to little over 38k (8k more on youtube) but not before long it grew again to nearly 32k (AGAIN 9k more on youtube) and later it grew much more to 42k (9.5k more on youtube)
YEA JAPAN LETS GO MY WEEB FRIENDS! (why akm playing for japan and france tho kappa) my new favourit team (tho still after frogue)
My thoughts
even tho this qualifier has much better teams it has less viewers (30k avg) then shanghai had (50k-70k) most likely cause are terrible hours for eu viewers (where most teams in this qualifier are from) with stream starting at 2am cest and ending before 8am it was preaty much impossible to watch if you're from europe (and when eu was waking up at 8 we saw rapid increase in viewership from 30k to 40k). i was not aware of youtube stream during shanghay wualifier and was preaty suprised by the numver of viewers it has, even tho it never broke this 10k mark
PS. "Number of viewers for the Overwatch World Cup Shanghai Qualifiers" that is what mod changed my last posts tittle to but it turns out its far too long and i cant make thread with such a tittle, so im not sure if its a feature or just unintended but mods can create much longer tittles ;)