In my experience fireline is cut very easily. More easily than braid and
certainly more easily than mono. This is, is you compare lines of roughly
same B.S., or superlines with up to 2 times the B.S. of mono.
If I fish deliberatly for pike, or even in waters with a good chance of pike
biting, I always use a steel leader of some kind. I don't want to lose that
big one, even if he does swallow my lure. And to my knowledge so far
everything but steel (or rather metall) has been cut by Pikes teeth sooner
or later.