I would not be surprised if they have increased the capacity. If they have not been selling a lot of tickets this summer (and they must not have, for them to invite bloggers for free, to get this huge marketing push) then they were not making money on this. So there would be no financial reason for them to cap the number of tickets sold if this big marketing campaign works.
It would be a shame if all of the videos showing how “the park is empty and every ride is a walk-on!” cause larger crowds to come, since the whole reason for this event was to admit only a small number of guests. This would be similar to a great restaurant getting rave reviews, becoming suddenly popular, and letting quality decline due to large crowds. I hope that WDW does not allow it to happen, but I don't know if they would turn away money in order to preserve the guest experience either.