Is this internet connection enough for streaming (Twitch)?
Sufficient for 720p60 with a 3500-4500 bit rate.
If the upload remains at 7 Mbit, it is a 720p to 1080p stream with a maximum of 6000 bit rate. However, I recommend 900p at a bit rate of 4500. You should always have about 20% reserve.
So yes, streaming is possible.
Is it enough for other games in the background?
You are confusing upload with download.
These are 2 different things. When streaming, you upload (upload), while playing you download (download). So yes, enough for both.