My understanding, from my old website development projects as much as my hubpages, is that it is a bit of both. Fresh content is going to keep the hub from slipping in the Google rankings, as well as making sure that pictures and video are featured. Getting the right keywords is always going to be important, so analysis of the topic using the Google keyword tool is necessary to tune the content (but not overload).
My view is that decent content will build backlinks over time from 3rd party websites and blogs, but you need to publicise through social media to reach the audience in the first place. I am against the concept of spamming sites with my links, unless I own the site in the first place, and the link is in context of the content being linked.