Iran, who scored their fourth consecutive victory en route to making the Kuwait 2022 semi-finals, will face the winners of the Thailand-Tajikistan in the last eight tie next.
Hossein Tayebi netted a hat-trick and Salar Aghapour, Alireza Rafieipour, Mohammad Hossein Bazyar, Moslem Oladghobad and Saeid Ahmad Abbasi scored a goal each.
Pham Duc Hoa scored the only goal of the Vietnamese team in the final minutes of the match.