Phonetically, and this straight from a native of that fair city:
Yeck-ah-tyer-in-BOORG (first four syllables prounced swiftly, accent on the final)
Oh, and natives do NOT believe that both are correct and are typically annoyed when the name of their city is mispronounced, especially the incredibly uncouth (but oddly not uncommon) "Eee-cat-ah-REEN-burg".
Gross!