A lot of people like to use a second pc for streaming these days so that may be something to consider if your concerned about your fps
As for ram, 8gb is fine if the game is the only thing running. At least for rainbow six siege it uses 5gb ram, along with system use of about 1-1.5gb which doesn't leave much. Open a browser and there goes my remaining capacity.
I believe others have experienced this to some degree which is why 16gb is recommended for system builds.