All you have to do is hear the buzz in town and see the sellouts whenever they come to play to know something still exists.
The Steelers are a massive draw anywhere they play in the NFL. It really doesn't have much, if anything, to do with any rivalry with Jax.
I've seen the Steelers in Cincy many times, Cleveland, Charlotte, and D.C.
Every one of those games were packed full of Steelers fans.