[nonsporting]

Except that the "that" (the singular neuter demonstrative pronoun) is not referring to faith (a feminine noun); rather it and the subsequent "gift" (a singular neuter noun) are referring back to "the overwhelming wealth" (a singular neuter noun) in the previous verse 7. It's the "overwhelming riches of God's grace" that is the gift that we receive through faith.

[touto] (that) is neuter singular. [ploutos] (wealth) is masculine singular. It is unlikely that [ploutos] is the antecedent for [touto], otherwise we have an agreement error.

[touto] can reference a verb phrase: "[by grace] are ye saved". We know from many other contexts that "salvation" is the "election of grace" (Romans 11:5-7)

[aruanan]

[touto] (that) is neuter singular. [ploutos] (wealth) is masculine singular. It is unlikely that [ploutos] is the antecedent for [touto], otherwise we have an agreement error.

πλουτος is either masculine or neuter. In the case of Ephesians 2:7, it is neuter as seen by the neuter definite article and adjective το υπερβαλλον. There is, therefore, no agreement error.