I read this:
His estimate of a reasonable revenue for a partner is $2 per 1,000 views. If we extend that to 1,000,000 views, we would expect $2,000 in revenue from a video with 1 million views.
And this:
On an average, $1 for 1000 views. So 4 million views would mean about $4000, could be more, could be less. It was reported that the Gangnam Style video, which had over a billion views, made about $8 million.
But to be eligible to get a payout, you need to be a partner; once you get a good number of views, you'll easily be accepted.