If a player goes on IR before the 53 man cutdown, they are out for the year. Only way they play this season is if they cut an injury settlement and go sign with another team.
If a player makes the 53 then gets put on IR, thanks to covid rules they can be added back to the roster after a couple weeks. At least 3 I think.
I don't believe they can participate very much until you bring them off of IR, so at some point you gotta give em a roster spot or PS squad him.
If the Jags don't wait and IR Travis right now, he is not playing for the Jags this season. and of course, they would not give him an injury settlement and let him walk.
If they fit him onto the 53, they can then put him on IR and call him up later in the year when healed, which would make sense to do if this was like a 3 month injury timetable.