Bismihi ta'ala
The grand scholar, Ayatullah al-Udhma Seyid Abu al-Qasim al-Khu`i (1317/1899 - 1412/1992 AH/CE) was one of the outstanding Shi'ah jurists between the sixties until the early nineties.
For a detailed biography on his life, please refer to:
https://www.al-khoei.org/grand-ayatollah-al-khoei/
As far as his teachers are concerned, he studied under the greatest of scholars of hist time. Among them were:
1. Sheikh Fathullah Esfahani, known as Sheikh al-Shari'ah.
2. Sheikh Mehdi al-Mazandarani.
3. Sheikh Dhiya' al-Din al-'Iraqi.
4. Sheikh Muhammad Husain al-Gharawi al-Kumpani.
5. Sheikh Muhammad Husain al-Na'ini.
And others. However, from what I have looked into, I have not come accross information stating that the late Seyid al-Khu`i studied under the late Seyid Abu al-Hasan al-Esfahani (1284/1867 - 1365/1946 AH/CE).
As for some of the prominent students of Seyid Abu al-Hasan al-Esfahani, who are famously known, they are:
1. Seyid Mahmud al-Shahrudi.
2. Seyid Muhsin al-Hakim
3. Seyid Hadi al-Milani.
4. Mirza Hashim al-Amuli.
5. Allamah Tabatabai.
And others.
And Allah knows best.