The question is in the title. Looking at a config where they were trying to Peering traffic over an SVI, but they have the physical interfaces bandwidth listed as the value and I am not sure if that is correct.
VPC isn't really relevant here. All SVI's (whether mapped to a VPC peer link, some other random trunk or just a bunch of access ports) end up with the same bandwidth value by default. You can adjust it manually or, indeed, you can set the derived value your IGP uses (...if applicable) but there is no automatic correlation between the underlying physical link and the value assigned.