Depends on the traffic of the website and how long the visitors stay on it.
According to coinwarz you can make $5.1 for 24 hours of mining on CPU/GPU, but realistically (for an average visitor) probably closer to $1/24hrs. If we take Reddit, which has 13 minutes average visit, probably between 5M and 50M daily visits.
That's $45K - $451K daily revenue.
That's probably more than their ad revenue.