Need a brief explanation of the grammar of って when it means "if ... then"

Question

The って I'm referring to is in the sixth line of the lyrics of a song called Don't you see! And it is right after 楽になる.

信じる事を止めてしまえば　楽になるってわかってるけど

Judging from three translations of this song I have been able to find and two Japanese-English dictionaries, it seems to me that the って here means "if ... then". However, despite my hard searches, I haven't been able to find its grammar (in this meaning) such as under what conditions it can be used or what words it needs to be used together with.

An brief explanation would be much appreciated.

Answer 1

This って is not related to "if ... then" described here.

This って is simply a colloquial variant of the quotative marker と, which is used with 分かる, 言う, 考える, etc.

If you saw "if" in someone's translation of this line, that's from the conditional particle ば in 止めてしまえば. Parse this line like so:

「信じる事を止めてしまえば、楽になる」ってわかってるけど