How do you pronounce Isaiah?

Ai-Zay-Uh would definitely be the most common. I'm not sure I've heard it any other way.

Eye-zay-uh.

I'm in Canada and would pronounce it eye-ZAY-uh.

eye-ZEYE-uh in the UK. eye-ZAY-uh in the US.

it will generally be Ai Zay Uh

I’ve heard Eye-Zay-Uh pretty much exclusively from people who only speak English. I’ve never heard the first pronunciation you wrote. For people who also speak Spanish though I’ve heard other pronunciations like the third version you wrote. “ee-sai-uh” the hispanicized version of the name is pronounced “ee-sai-ee-ahs” In English it’s pretty common to keep the pronunciation of a name and the original spelling from the persons culture (or an approximation with English phonemes) Jose will either be pronounced normally, or as “Hoe-say” by those incapable. You wouldn’t pronounce it “Joez”

For what it's worth, I think that Ee-Sai-Uh is going to be closer to the original Hebrew pronunciation.

Okay this one differs between U.S. and UK English in the second syllable. U.S. English uses “zay”, rhyming with “say”, while UK English uses “zai”, rhyming with “sigh”.

I-zay-uh is the more common pronunciation, but a few others are occasionally heard. This pronunciation is the default pronunciation for people with the name, though sometimes people will let you know they prefer a different pronunciation. I-zigh-ah and I-zigh-uh are both somewhat common, and other pronunciations pop up from time to time, usually in regards to the Hebrew prophet or his writings. edit: I didn't mark the stress/emphasis syllable(s), that is yet a further complication if you really want to get into the weeds.

You mentioned Hebrew, so it’s worth noting that the original Hebrew pronunciation of the name יְשַׁעְיָהוּ (yi-shai-YA-hu or if speaking quickly just yi-shai-YAU) is far removed from the customary pronunciation in English and other western languages. That’s hardly surprising given that the name arrives in English thousands of years after the prophet Isaiah flourished, and the name has gone through transliteration and approximations into Aramaic, Greek, Latin, French, and Middle English along the way. The same is true of virtually any biblical name. You will, of course, find little boys named Yishayahu among the most strongly traditional-minded communities of Jews who are exiled to the Anglosphere.

All varieties of English, AFAIK, would pronounce the first syllable as “eye.” That’s the pretty standard pronunciation of the “long i” sound in English. Lots of other languages pronounce that letter as “ee,” though, so those languages would pronounce it like your third option. As lots of other commenters have said, the pronunciation of the second syllable will depend on which dialect of English you speak, so both “zay” and “zigh” are used in different areas. I’m American, so I’d say eye-ZAY-uh. If someone introduced themselves as eye-ZIGH-uh, I would guess they were from the UK, Australia, etc. If someone introduced themselves as ee-SIGH-uh, I would assume they are from a non-English speaking country.

The only time I’ve ever heard the first syllable pronounced “ee” is when Latinos use it as a given name from Spanish *Isaías* (ee-sah-EE-ahs). This isn’t terribly common.

I believe this is an American vs British difference. I've always heard Eye-zay-uh in America but sometimes hear British people say Ee-zy-uh

Eye-zye-uh Where "zye" rhymes with "eye".

Ai-zei-a Is how I say it

British English, the old joke is "one eye's higher than the other" - you just drop the 'h' from 'higher', as most brits will do in normal conversation.

US: eye-ZAY-uh UK: eye-zEYE-uh

I’m a British English speaker and for me the first two vowel sounds are both pronounced the same as the word “eye”.