If the Western world admitted 100% of all prospective Syrian refugees, the amount of lives that would be saved is the same as the amount of lives that would be saved if we admitted none whatsoever: zero.

Europe, the U.S. and other western powers do not send military forces into Syria to collect civilians and then send them to the West. The 'Syrian refugees' we admit are not taken directly from Syria, but from refugee camps in neighbouring nations, chiefly Turkey, Lebanon and Jordan. There is no existential threat for the people living in those camps. They are as endangered as anyone else living in Turkey, Lebanon and Jordan. What's more, the vast majority of these people don't want to be sent off to the West. They want to go back home, to Syria, but to a Syria that is safe for themselves and for their families. The notion that there is a life or death need for the West to admit these refugees, or that by refusing to give them a new life in the West we're somehow playing into ISIS' hands, is false and absurd. If Western governments would like to help the situation in Syria, they can stop creating Islamist organizations in the first place. If that's not enough, they can take the funding they were going to spend on giving refugees permanent accommodation in the West and instead direct it towards providing assistance to international relief organizations operating in the refugee settlements.