News Courtesy of Yoast.com:
Google Ads and organic rankings
“This is a much-debated topic in the SEO world. The thing is, that as your overall site engagement increases, your site usually does better in search as well. It doesn’t matter whether that increase in site engagement comes from Ads [AdWords] traffic, Facebook traffic, or anywhere else. If you get more traffic to your site, more people search for your brand, and are talking about you online, you will do better in the search. It’s that simple.
Ryan’s Take 
It’s definitely a nice bonus when you start seeing keyword rankings rise in the SERPS when running a Google Ads campaign. While some people might cry foul and think that Google is rewarding them for using their paid ads, I truly believe it is user engagement that causes this increase. However, I don’t necessarily agree that traffic of any kind can cause your keywords to perform better in Google.
When someone clicks on your Google Ad or organic listing that information is tracked. Google knows if you hit the back button and continue searching. They’re able to determine if the user is not satisfied with the result they clicked on. The term pogo sticking is used to describe this behavior. It’s the opposite of what you want to happen. On the other hand, bounce rate (the percentage of visitors who view only a single page), is not necessarily a bad thing. It might be that they had found their answer but do not need any additional information from your website.
You might be wondering how Google determines what the user engagement is. How do they know the time that visitors spend on your page or website? They’ve said that their Analytics data isn’t factored into their algorithm. Therefore they can only track external information such as clicks in organic and paid listings. I have a hard time believing that a Facebook post, not indexed by Google but driving a ton of traffic, could be used to measure user engagement. There has to be some way for Google to track time spent. Still, if you can generate brand mentions or backlinks from referrals, your keywords for that page will increase in the SERPS.
