Ok so the guy needs a camera for amateur video/vlogging/photography, tells you he would prefer to stick with Canon because his partner has a 7d, therefore, probably has lenses they can share. He also has used Canon before and probably is more familiar with it in general. He also says he is not knowledgeable in photgraphy etc.. Can you please give me 1 reason why he shouldn't just stick with Canon? In what way would an 80d or t7i not fulfill his needs and more so? Does he need 4k recording right now or in the immmediate futre? what about the g85, or any other mirrorless camera is it that should move him towards it? Is it better on a specsheet, sure, but is it substanitally better in the real world for this guys usecase? NO it is not.
This is a general comment, and you 2 are just the 2 people that have made the recommendation this time round, so don't take it that personally, although I understand my tone is somewhat agressive. I understand most people believe that mirrorless cameras are the best thing since sliced bread, although for the life of me having used loads can't figure out why. BUT, you also have to understand that the specs they offer are not always necessary. The best way to put it is this, a ferrari is a great car. It doesn't mean everyone should go out and buy one. Most people are much better off with a VW golf.
OP, the t7i is more camera than 90% of the schmucks who use one can handle, its a lot more camera than most people need or will ever be able to get the best out of. I would say go for a used one to avoid getting hit be depreciation, but it is more camera than most people will ever need.
Don't go for the 80d. The t7i is as good or better in most ways, it is truly an amazingly well specced camera for its market segment. The only caveat is if you need to check levels when recording video the t7i doesn't have that capability, in all other aspects, its at leats 95% the camera the 80d is. Yes, the 80d is due for replacement. But, even if it were replaced tomorrow, it would still be more than adequate for your needs. In short, the best thing for you about the 90d is that it will drive prices down.
Just go for the t7i. Buy used if you can so you avoid the depreciation.