For the same niche and same set of keyword, does google adsense serve higher cpc ads to a website that has higher number of visits ?

I have observed that for similar niches 1 website (with 3K daily uniques) makes around $100 a month, and another website (with 10k daily uniques) makes around $700-800 a month

it seems that the earning curve is not linearly dependant on visit count and somewhat increases at a rate faster than the growth of visits, this leads me to think if the google adsense algorithm serves higher cpc ads once a website starts getting large number of visits.