In Matches, each pair needing review gives you two options: Confirm match or Not a match. Confirmed pairs have no review actions.
Confirming links the lead to the Xero contact and adds the pair to Confirmed Matches. Revenue is attributed only when there is an eligible paid invoice; confirming an unpaid pair or a pair without an invoice does not itself mark the lead as paid.
Choosing "Not a match" dismisses the suggestion — the lead stays unmatched, and no revenue is attributed to it.