They're independent factors, we reward your CPM as we receive it from the advertisers and we don't hold it conditional to any of your accounts stats. We mainly use the approval % to prioritize the video going on the live queue, but there's a few other factors we consider as well.
I've been confused about the rating for a while as well. My rating is 65% but I've never had a video get rejected. The only thing I can think of is that whenever I get offered limited distribution (almost always), I delete the video and reupload under just the Rumble Player license. Could that be affecting it? Although the math doesn't add up that way either.