how should that help? lower bitrate = worse video quality
I'm new to log reading but it seems like your input is 720x480 and than you upscale it to 1280x720. you seem to stream on twitch and not youtube so scaling it to 1280x720 is pointless because twitch doesn't reencode your stream.
If there is a network problem then lowering the bitrate would improve things. However it doesn't look like that's the case although the network numbers from the Twitch bandwidth tester are not great you can at least connect OK :-)
As far as the pixelisation appearing I think that
@TryHD hit the nail on the head. In your log it shows that the Roxio is set to 720x480. Can you post a screen shot of the following configuration page, right click the Capture card in Sources and choose Properties, select Configure Video and screen shot whatever comes up. You can use the snipping tool in Windows to easily capture the screen and then the Upload a File button to include it in a post.
Snip from the log just for information:
video device: Roxio GameCAP HD PRO
resolution: 720x480