Every Greek word has a gender (male, female or neuter) and things like nouns must have the same gender to identify which noun goes with which pronoun. Here is the verse with gender identified:
[Eph 2:8 NASB] For by grace[f] you have been saved[m] through faith[f]; and this[n] is not of yourselves, it is[n] the gift[n] of God[m];
“this” and “gift” are both ‘neuter’ in Greek, so whatever they refer to cannot be either ‘masculine’ or ‘feminine’. Therefore, Greek grammar will not allow any one of the following:
- grace[f]
- saved[m]
- faith[f]
to be either “this” or “the gift”. If any one of them was “this” or “the gift”, then the Greek would have not been ‘neuter’ but would have matched either the ‘masculine’ or ‘feminine’ of the word that was the “gift” and “this”. The only meaning that works with Greek grammar and a ‘neuter’ “gift” is for the gift to be both masculine AND feminine, thus making ‘neuter’ the appropriate gender for a mixed gift. In the verse (Ephesians 2:8), that means that both “this” and “the gift” are the whole phrase “by grace[f] you have been saved[m] through faith[f]” … grace, saved and faith are ALL “this” (“not of yourselves”) and “the gift” (“of God”).