He's gonna end up with a config like mine xD, 8 Core Ryzen, 16GB of fast RAM (3200mhz), a 256GB SSD and a 2TB HDD, thats a pretty basic and good config. For a GPU I have no idea what is best. I have a Sapphire Nitro+ Rx 580 8GB
Im not exactly the most PRO at computer building, but I'd recommend a 8 core Ryzen CPU, it seems to handle streaming and gaming simultaniously pretty well.