TLDR; 5000kbps for Twitch (
guidelines). 6000kbps for YouTube (
guidelines).
Depends on what platform you're streaming to. Each platform has their own guidelines for bitrates, but generally the idea behind it isn't what
you're capable of uploading, but rather what your viewers are capable of downloading and if the platform transcodes your stream for you to multiple lower qualities but also lower bitrates.
For Twitch, you need to be partnered before they will transcode your stream, at which point you can stream at fairly high bitrates because Twitch will offer multiple transcoded (lower quality, lower bitrate) streams for viewers who aren't able to download the original bitrate quality (they will buffer). If you aren't partnered, stick to the guidelines linked above as your original quality is the only quality that will be available for viewers. A viewer with a 5mbps download speed for example won't be able to view a stream of 6000kbps (6mbps) without it buffering (not accounting for audio bitrate). YouTube on the other hand transcodes livestreams for all their streamers.
