Is "it" referring to "to be alive"?

Yes.

fire1"it" is used to refer to "to be alive".

Yes, in the sense that you are using 'refer', but technically 'it' does not refer to anything. It's "non-referring it", which is a place holder for the infinitive construction 'to be alive'. This is also called "dummy it".

CJ

fire1I think in this part "Bliss it was in that dawn to be alive", "it" is used to refer to "to be alive".

I think it is more the sensation of "bliss." but CJ is correct in that this is an expletive "it" as a grammatical necessity, but without specific meaning.