Your pc can run R6S , i run a gtx 1060 6gb and a amd fx-8350 and get around 60fps on high-veryhigh, you should get more fps as you will most likely be running a 1920x1080 monitor, you would get around 100+ fps, i run a 2560 x 1440 i get a higher quality as it's 1440p so you can easily run siege on your pc specs
* UPDATE *
I would recommend anything over 8gb ram as siege can occupy sometimes upto 4/5GB of ram when playing..