As mentioned before, the mainland (Mandarin) rendering of that name would be Xie Shu-wei (pinyin) as opposed to Hsieh Su-wei (Wade/Giles). "Xie" is pronounced differently in different Mandarin dialects, but a little bit like "s(h)jeh". The initial consonant is a voiceless alveolo-palatal sibilant that doesn't exist in many languages (like English, Modern Hebrew or Eastern Arabic, but it exists in some Scandinavian languages (Dutch, Danish, Swedish - "sj")).
However, as Hsieh is not from the northern mainland, all that doesn't matter. In taiwanese Mandarin, the diphthong "Hsieh"/"Xie" is inverted in a way, not "i-eh", but "eh-(y)" and the "Hs" is often pronounced a little bit more "juicy". So basically: "shay" (with a tendency to "sheh").
Additionally, "shu" (northern mainland Mandarin) is pronounced and transcripted "su", like in southern mainland Mandarin.
If you pronounce her name "Shay Soo-way", you are pretty safe. Bonus points for correct tones, of course.
Is Hsieh/Xie related to the word "xie" meaning "thanks"?
Thanks for pointing that out. I was pretty sure that 'vahz' is the way they pronounce it in (most of) UK, at least they taught us, but I only suspected that it differs in America. Indeed, it was the British pronunciation I had in mind.
Being european, you were taught the british way.
But here in South America, they teach us the american way of life!
And that's why it's so tricky to write about pronunciation.
Even using exemples of a language we all know, many things can get lost "in translation"...
Your confusion is completely understandable, because--without any warning--you hear some of the names pretty close to how they should sound, and some of them always mispronounced: Sharapova is the best example here, the incorrect english pronunciation is more-or-less the only one used outside of central and eastern Europe.
It is true that the rules on where the emphasis should be, differ among slavic languages. In Bulgarian and Russian, it can be (in principle) almost anywhere. In Czech and Slovak, the emphasis is marginal and (almost) always on the first syllable.
HOWEVER!: There is one common rule which anybody can follow without making a mistake. The -ova suffix is NEVER pronounced as it would be in English. The single vowels correspond to constant sounds, and 'o' should never be pronounced as in 'cope' or 'over', but always as in 'slot'. The 'a' at the very end can be short (russian, bulgarian names; like in 'stunt') or long (czech, slovak; like in 'vase').
What about Petrova, Kuznetsova?
Bitttchhhhhhhhhhhhhhhhhhhhhhhhhhhh You Better Pay It Honey! The Devil Is A Liar!!!!! Bitches Get Interviews And Shit? Where They Do That At Honey? Girls Are Late Honey!!!! The Queen Needs To Get Into It Honey Cause The Girls Is Late Out Here! Yes Honey Im Throwing Epic Shade!
A good general rule with East Slavic languages(Russian, Bulgarian,etc.) is to place the accent on the second syllable, although Russian accents are all over the place, and long names put accents towards the middle.
Bulgarian is not an Eastern Slavic language, but Southern. Bulgarian and Russian have floating accent, so no general rules, you will only lead them to errors.
Julia Goerges, but only because I hear commentators use about three different pronunciations for her name and I don't know which one is correct
Julia should be simple: Yulia. Goerges is easy too: both "g" are hard (as in English get), and German "örg" is basically "erg" in English (like the pronounciation of English "Berg" (NOT American English, of course)). Her own dialect sounds like a North German dialect, so don't speak the "r", just modify/drag the vowel like many British dialects do.