Traffic will go up and down from day to day. There are good days and bad days. However it is always good to look at ways to improve traffic.
Start with the Hub itself. Is it well written, informative, interesting and something people will want to read. Also is it well laid out, with good spelling and grammar etc.
Use images and follow some of the recommendations given regarding amount of words, pictures and other modules.
Being a featured hub is not just about the traffic, but the Hub itself and how it is put together.
The score of the individual Hub will determine whether Hubpages let's it get ranked in Google. Also your personal score (visible on your profile picture on your profile) will determine this.
Next think about Search Engine Optimisation. You need to know at least something about this to write your Hub in a way that is interesting to human visitors and also ranks well in search engines like Google.
If you simply write a hub and leave it to produce it's own traffic, you are likely to find it is slow to build up and even peaks then drops. Marketing will help you. If you have a Facebook page (if not maybe create one), you can build up followers on facebook and each time you write a new Hub, post the link there. Also use other tools, like Google+, Youtube (for videos), Twitter etc.
If you have a particular hub that you feel you want to push, create a link to it in your email signature, so that everyone you email will see the link and possibly follow it.
Writing the hub is part of the process. Marketing it is another entire area. It depends how much time you are willing to put into that. If you feel you want to only write and hope search engines will bring in some traffic, then it may go slower.
Also, the more hubs you write, the more followers on Hubpages you will build up; and the more Hubs you have, the more places you will rank in search engines. If people like what you say in one Hub they find, they may go visit more of your Hubs.
I hope this helps