Yes. Sure
Almost any computer is capable of streaming.
its more that while playing game/ creating video most power of processor/graphic card is already used on this and on the top of you need to run program that streams to Twitch. bear this in mind.
So more demanding game you play the less power is left for streaming.
Yes your processor and graphic card is capable of sending full HD video 1920×1080 but while playing very demanding game you will have to either lower resolution/framerate of stream or the actual game.