I haven't been on hubpages long enough to answer this question with any authority, but I have been running websites and using SEO since 2004. And general SEO rules apply to hubpages, one would think.
1. It takes time for your webpage/hub to be noticed by search engines. Webpages are like wine; they get better with age.
2. I don't think traffic has anything to do with your hubscore.
3. Factors to improve hubtraffic: keywords, related keywords, internal linking, backlinks, and length of the hub.
There are plenty of hubs that explain each of the above factors.
Hope this helps.