I was following /pol/ since Trump's campaign started, back when I was certain he was just a sideshow distraction. Donald Trump's twitter account even winked at /pol/ at one point by tweeting what a 4chan poster asked, as well as copying their meme images. There was and is a very close connection there. It would be difficult to quantify the notion that the absence of /pol/ would have lost Trump the election, but I wouldn't be surprised if that were true.