In the English Wikipedia, his full name is spelled as "Joachim Anthoniszoon Wtewael". The middle name as the suffix -zoon (son of), which explains the somewhat weird "sz". The pronunciation of the last name is given as [ˈyːtəʋaːl] in IPA. So the initial W corresponds to a U in modern Dutch. https://en.wikipedia.org/wiki/Joachim_Wtewael And by the way: In Wtewael's times there was no Dutch or Flemish state yet, but it all belonged to the "Holy Roman Empire of German Nation", and the language was just one variation of a Lower German dialect (which later developed into the Dutch language). So you are not entirely wrong to post this here (though the Duch section is certainly more appropriate).

As he was Dutch, maybe you would have more luck asking this as a question about Dutch rather than German.

Oh, thank you. I have just noticed this name is Dutch, not German. I thought German sounds similar to German.

Maybe somewhat like "Yo-uh-keem Un-tone-ish Oo-ee-ta-vale"

I could be wrong. The name looks interesting, but is not typically german. The first name does exist in Germany, the middle name looks eastern european to me and the last name in the beginning "wrong", and in the end dutch. The "sz" would be spelled "sh" in english, the "ae" like an "a", (as in whale), and the "ch" in the first name is a sound english doesn´t have. English tongues would spell it "k" but it is rougher. I could have googled first. He was a dutch painter. Let´s see if there are experts, spelling it in english would make things more complicated, but the "J" would be a "Y".