for me it's the 2nd one.

vad part of nevada rhymes with mad or bad

it's the only way i've ever heard it said. i'm over 50

an internet search found this

It's important to note that the "vad" pronunciation in Nevada is a regional feature of Western U.S. English, particularly among residents of Nevada, and is not commonly mirrored in other words outside of place names or regional dialects.  The "vah" (long "a" as in "spa") pronunciation is more common in Eastern and Southern U.S. dialects and is ...

often considered incorrect by locals.

Locals pronounce it nə-VA-də.

Nev-uh-day. Just to fuck with people from Nevada. 😌

On the east coast, I say "Ne-vaugh-da" and the other always sounds to my ear like a kind of old timey out west version. Like, I hear Sam Elliott saying it that way in my head.

are they from boston. the first part is nay va. DUH!

It's both. The original technically correct version is with Spanish pronunciation because it is a word from the Spanish language. Many people from Nevada, especially white folks, don't like the Spanish style pronunciation and insist it is wrong. I personally prefer the Spanish pronunciation because it's funny when Nevadans get annoyed over it, and I hate bigots.

https://en.wikipedia.org/wiki/International_Phonetic_Alphabet