GFE is the same and they've since branched into a couple other games including HS, SSB, Rocket League,... No idea how they are making money but they are continuously expanding.
I feel like major sponsors are taking out their Blizzard frustrations with the Overwatch league on Hots. Like alluded to above, there is no reason for Vainglory to have all the major sponsors, while HOTS has basically only Tempo
Oh to add more fuel to the gossip fire, remember when nvt announced that kenma would coach? Apparently he hasnt coached them once because nvt "couldnt afford to pay [him]", a little hard to interpret because kenma has a really high opinion of himself and could have been asking above his pay grade, but could also be interpreted as "nvt doesnt have money", conjecture is fun. That's a pretty big stretch tho and you cant really fault nvt for not wanting to keep kenma on payroll