I have found that income increase is less based on viewership from the aspect of having many followers than it is on viewership for specific articles. If you write an article that is an "evergreen" topic or something that many people are searching for on websites like google, you will see a great increase in traffic and, thusly, in income.
For example - I wrote a Hub on Homemade Christmas crafts, which recieved a high amount of traffic in November and December of 2011, which greatly boosted my income on Hubpages for a few weeks. Since nobody is looking for homemade Christmas gifts in January, my viewership and income have decreased again.
I hope I helped! Good luck!!