It has been about two years since Google announced they were including HTTPS as a ranking signal. Like most new ranking signals however, the amount of pull HTTPS started with, and has now, appears to be very minimal. But as popularity for HTTPS grows so will its influence on search results.
What does this mean right now?
If your current website does not use HTTPS do not worry. While HTTPS is a positive improvement for any website, right now it does not appear to negatively impact SEO. Google is not favoring HTTPS as a whole against HTTP websites, but rather giving them a one up on competitor websites, around the same search rank. Google will always want to provide the most relevant search results because they want to provide the best user experience. HTTPS is an improvement for user experience and is why Google made it a ranking signal.