Fans come and sometimes go, I don't hink it's directly related to the number of hubs you write, but the more hubs you write about various topics could attract more fans.
The best way to increase your fans, is spend a few hours each week or each day, if you can, reading others hubs, finding something you are interested in or like, join their fan club and leave fan mail telling them why you liked their article. They will normally go to your hubs, read them, and do the same to you, and then you begin to build relationships with your readers and they, you.
I would also like to say, that while some might join your fan club, it doesn't necessarily mean they will always read or comment. So, you have to keep reading others, and commenting, and adding to your pool of fans. I know some authors only have a few fans, and they are very good writers, and vice versa. I'm afraid I've read some authors who either because they write a "hot" article, perhaps writing about a sexy subject, and they'll get a lot of fans, but they might not be that "good" of a writer.
It's all a matter of opinion. Don't set your heart on fan numbers, just write, read, and try to be sincere.
Scores and fans go up and down on Hub. =)) good luck to you!! Mainly, learn some things, and have some fun!!