8 belongs to the standard 1–9 range recognized by every mainstream numerology school as a valid life path result. There's no separate approval process for it — if your digits reduce to 8, that's your number.
8's cultural reputation is a little different from most single digits: rather than mystery (7) or beginnings (1), it's most often tied to material outcomes — money, authority, achievement. Some of that traces to East Asian numeral traditions where 8 is considered auspicious for reasons entirely unrelated to Western numerology, and some of it is a more modern invention layered on by 20th-century numerology writers. Either way, it's tradition stacked on tradition, not a property of the digit itself.