Theoretically, if players were to scratch a session and were waiting to stop existing, would a GT Sylph of Hope be strong enough to say 'you know what Fuck this' and use their power to create hope to essentially create a space where the hope of the players and therefore the players can survive?

Yooooou could make a case for something like that, I’m not sure if Hope would be the best choice of Aspect to survive a Scratch, but I could see that being the case. Something defensive that pretty much creates an extra-Dimensional Bubble that remains unaffected by the Scratch, effectively erasing everything around them and leaving them suspended in the middle of the Furthest Ring where the Session used to be… Left floating in the middle of Eldritch Calamari Land.