In my experience, votes don't affect SEO nearly enough.
Almost every problem I search for turns up multiple SO results, and frequently one of those is clearly the definitive version of the problem on SO, but it's rarely the top hit.
As an example, searching "android spinner prompt select" on Google* right now turns up three dupes and one unrelated question all outranking the definitive question. The definitive question has 100 times the votes, was more recently active, has many more views (despite apparently subpar SEO), and otherwise seems potentially SEO-deficient only by virtue of being older (which could be a positive factor in this instance). I wish that Google would take into account posts' votes, but I haven't seen any evidence that they do.
Expecting Google or other search engines to take internal vote counts into account isn't really realistic, but it sure would be nice if there were some general mechanism for sites to offer suggestions to search engines about the relative ranking of their own content. Just as
<meta name="description" content="..." /> can be used to hint how a page should be summarized, it'd be nice to have some similar
<meta name="quality" content="<question score>
" /> to hint that relative to other content on the domain, this page is a keeper.
Maybe some day...
*Of note is that DuckDuckGo gives much better results. A new challenger arises?