Are these values enough to stream on Twitch and upload YouTube videos?

I have a 50 k line.

Further data:

Yes should be enough

Will I get problems / lag in games then?

Yeah, it can stream smoothly in 60 FPS ~ 800p resolution and a 6000 bit rate, overwatch.

That depends on your PC.

As bycrix1 says, it depends on your PC and the stream quality. In multiplayer games, you shouldn't sacrifice all of your upload bandwidth for the stream.
Here are Twitch's guidelines: https://stream.twitch.tv/encoding/