The relative importance of incoming traffic to a website with regard to organic search engine visibility is tied to a number of qualitative metrics. It’s not the sheer volume of visitors that Google evaluates as ranking criteria. Instead, their algorithm focuses on the behavior (bounce rate, time on site) and the source of the originating traffic (domain/page authority). However, Google will take notice if an increasing number of authoritative websites are sending site visitors.
Once a new traffic source is discovered, it typically takes Google around 3 months before associated signal weight is applied to search engine rankings. Keep in mind that incredibly authoritative traffic sources tend to speed up the process.