What is the time interval between the Maghrib and Isha prayers? Do jurists differ on this? And must Isha prayers that were performed based on an incorrect time estimate be made up?

The time interval between Maghrib and Isha is not fixed in minutes. Rather, the end time of Maghrib is the beginning time of Isha, marked by the disappearance of the red twilight, according to the preponderant opinion of scholars. Scholars have differed regarding the beginning time of Isha. The majority of scholars hold that it begins with the disappearance of the red twilight, while Abu Hanifa was of the opinion that it does not begin until the white twilight has disappeared.

As for making up prayers, if you prayed any of the prayers before the entry of Isha time and the disappearance of the red twilight, then you must make them up. As for what you prayed at the correct Isha time, you are not required to make it up.