If you're asking if you can make pop-up turrets fire multiple shots after each delay, no you can't do this from a map editor. You'll have to use SOC to either add more firing states, or to make it use A_TurretFire and A_TurretStop instead of A_JetGShoot.
These changes will apply to all turrets in the game, and since the ability to set the delay between shots is hardcoded to Mobj number 12, creating a copy of the turret with its own thing number to make the changes to will not give that copy the map-based shot delay, and you'll have to set one delay via the states to apply to all uses of the copied, custom turret. Naturally you could just make a new copy of the turret to give a different delay to each of them, but that's pretty tedious.