This would essentially work like pro football or baseball or soccer. This sort of thing has almost always made these sports much more popular and would probably serve to grow the competitive side of GW and would also help the PvE side by making the GW side more healthy and offer no intrusion or immersion disruption to PvEers since its only in observer mode "TV".
However many people just resent advertising in general, especially on a product they paid for, of course people pay for the both TVs and cable and still tolerate advertising, but the networks are not selling the TVs

How many people would have a problem with such a thing?
Obviously no one really wants to see adds, but I personally would tolerate it if it was going towards PvP prize money players had a chance at.