Chinese (Mandarin)
* Dàiyú (simplified Chinese: 黛玉; traditional Chinese: 黛玉) is pronounced "day-yoo".
* The "ai" sounds like the "ai" in "hair" or "stair".
* The "yu" sounds like the "u" in "flute".
Japanese
* Taiyu (太裕) is pronounced "ty-oo".
* The "ai" sounds like the "ai" in "aisle" or "aisle".
* The "yu" sounds like the "oo" in "moon" or "food".
To be sure of the correct pronunciation, you need to know the context. If you see the word "Daiyu" in a Chinese text, then it's likely the Mandarin pronunciation "day-yoo" is correct. If you see the word "Daiyu" in a Japanese text, then it's likely the Japanese pronunciation "ty-oo" is correct.
Let me know if you can provide more context, and I can give you a more specific pronunciation.