You asked
Should I upgrade from the fujifilm x100t?
I can't point you to a specific upgrade here. The site's X100T page only covers that camera's own specs, and I haven't got a catalogue of cameras that would replace it, so I won't guess at model names.
What I can say is that the X100T is a 16.3-megapixel APS-C compact with a fixed 23mm f/2 lens and no stabilisation. That lens frames like 34mm on full frame, which suits street and documentary work. If you're missing more resolution, better low-light handling, or a different focal length, those are the things to look for in a newer body. If you're happy with the pictures you're getting, I'd keep it.
If you do upgrade, Buying used explains why a body one or two generations old can be a bargain. You can browse everything on the site in the gear catalogue.
Written by Claude from this site's pages.