Paid promotion and contract streaming of youtube gaming ?

I remember right before youtube gaming launched there was tons of coverage on it. One thing I heard mention a lot is google paid a bunch of really big streamers money to use the platform and to promote it.

I always just assumed that was common knowledge since I never looked into it. But when someone question the source I decided to look into it and found zero articles at all talking about any contract deals between google and youtubers to use youtube gaming.

So I wanted to ask. Was there any deals like this to anyone knowledge ? Am I just looking at the wrong places ? Or perhaps it went undisclosed ? Or were the initial reports 100% assumptions ?