I always recommend having a minimum of 16GB... I mean, what if in a few months, he decides he wants to stream gameplay to Twitch? Then he'd need the extra RAM for encoding/decoding of the video, for running the program that's doing the recording, as well as for whatever magic Windows does to allow for multiple programs that have high bandwidth server connections (I actually don't know if that last one needs RAM or not).
Many people that get into PC gaming end up doing some sort of live streaming, doesn't have to be Twtich.tv