Science Fiction

but no evidence at all other than they are both on a space station. DS9 was developed by Berman, Piller and Rodenberry and even Strac says he doesn't think any of those three folks knew of Bab5 or the pitch he gave Paramount.

Plenty of differences right from the start. But let's look at the similarities.

Wormholes v. warpgates. Wormholes actually appeared in TNG as a plot device so saying their use means it was ripped off of Strac isn't very compelling.

Space stations as a the setting. Starbases have been around since the original ST so again, pointing to the setting and saying, see, ripped off, isn't very compelling.

Shapeshifting. We saw it in ST V (an otherwise horrible movie, did they rip that off from him too?).

A female first officer. Heck, that's in the pilot for the original ST.

An officer who is a Commander leads the station. Totally different rank structures, the equivalent for Sisko to the B5 rank would be Captain.

It's all just superficial stuff that doesn't survive an initial examination IMO.