This is a definite. Traffic always increases sales of a product if the traffic is focused. Evidence suggests this since people shell out significant sums of money for Adwords for specific keyword terms.

As an anecdotal example I used $100 Adwords voucher to drive traffic to my movie torrent meta-search engine https://moviemagnet.net on specific keywords: 'movie torrents', 'torrents', and 'movie downloads'. The most successful visitors by bounce rate and time on the site was for the most focused keyword, 'movie torrents' by a significant margin.

I'd love to see some white papers on the affiliation between sales and focused marketing to tech-savvy consumers, not just casual internet users.