These phrases are used to compare the Levite priests with Melchizedek. Your language may have a way to emphasize that the author is making a comparison.
It is never explicitly written in scripture that Melchizedek dies. The author of Hebrews speaks of this absence of information about Melchizedek's death in scripture as if it were a positive statement that he is still alive. This can be stated in active form. Alternate translation: "scripture shows that he lives on" (See: [[rc://en/ta/man/translate/figs-metaphor]] and [[rc://en/ta/man/translate/figs-activepassive]])