Is everything quantifiable? I'd say yes (but only in theory, practically, the answer is no). Any "thing" that is describable as a "thing," is quantifiable. In other words, "things" are inherently quantifiable. If something is not quantified, (I'm not only talking about with math) then it doesn't qualify as a "thing."
(We create/define "things." However, my usage of the idea "every thing" probably differs from yours.)
Does that mean that this is all just mathematics and nothing more? Absolutely not.
How could all of this just be mathematics if mathematics is just a part of all of this?
EDIT:
I should have said, I do think there exists that which is beyond math/quantitativeness. So perhaps I should have just said "No"
P.S.
This is not physics