I agree with the above responses that it is unlikely that you could turn down the job and still be eligible for benefits. And even if you could, it is likely that the UI benefit would be far, far less than working even with the paycut. UI really doesn't pay a whole heck of a lot.
It is quite possible, however, that you could accept the job and still be able to claim partial UI benefits BECAUSE OF the pay cut.
Two things I am tired of typing: 1.) A wrongful termination does not mean that you were fired for something you didn't do; it means that you were fired for a reason prohibited by law. 2.) The above answer, whatever it is, assumes that no legally binding contract or CBA expressly says otherwise. If it does, the terms of the contract apply.