I agree with most here that Poirier's chances aren't good, but I think it's still possible for him to win. He has to fight EXTREMELY patiently in the first couple of rounds, since Conor is most dangerous then. He also needs to land some good leg kicks--surprisingly, Conor doesn't defend those very often. Even though Conor's grappling sucks by UFC standards, his takedown defense and ability to get back to his feet are pretty good. If Poirier can do just enough to tire him out in the first couple of rounds, I can picture him snagging Conor in a D'Arce choke during a scramble. Also, another thing going for Poirier is that his fight IQ has improved a lot since he fought McGregor. With the exception of Khabib, Poirier has shown that he is excellent at bringing the fight to his preferred range and pace.
Sadly, chances are that this fight becomes for the LW title, Conor will just hit him with a straight left that KOs him in the first round, and then he refuses to defend the title until he boxes either Pacquiao or Jake Paul.