Is it allowed to combine and shorten prayers when one travels from Gaza to Jerusalem?

Answer

Praise Be to Allah and Peace Be Upon His Messenger.
Referring to your question, combining and shortening prayers is permissible so as to reveal hardship. Allah allows people to do that so as to facilitate certain issues when necessary. 
The majority of scholars say that the distance because of which a Muslim can shorten a prayer is 81 km going and 81 km coming back. The prayers which can be combined to each other are the two prayers of day: Dhuhr and Asr, and the two prayers of night: Maghrib and Isha’ as long as a Muslim is travelling. The four-Rak’ah prayer is shortened into two. 
Shaikh Muhammad Ahmad Hussain, the General Mufti (Muslim Legal Scholar), in the Palestinian Legal Verdict Council was once asked the following question: “I am an employee, and I commute daily from my town to the workplace. Can I combine Dhuhr and Asr and shorten them taking into account that the distance between the two locations going and coming is 130 km?”
He answered: “Basically, a Muslim should perform each prayer at its due time. Allah says: “The prayer is enjoined on the believers at fixed hours.” An-Nisa’: 103. 
Abdullah Ibn Mas’ud narrated that he asked the Prophet Muhammad (PBUH); “Which action is dearest to Allah? And the prophet replied: “Prayer at its proper time”. Related by Muslim.  
Nevertheless, Allah has ordained for you combining and shortening prayers because of travel and because of other considerable reasons. 
Ibn Abbas (RAA) narrated: “The messenger of Allah (PBUH) prayed Dhuhr and Asr together, and Maghrib and Isha’ together, and not out of fear nor because of travelling.” Related by Muslim.
The majority of scholars think that the distance because of which a Muslim can shorten a prayer is 81 km. Other scholars, however, allow shortening if the distance is even shorter. Allah says: “And when you (Muslims) travel in the land, there is no sin on you if you shorten As-Salat (the prayer).” An-Nisa’: 101. They say that the distance is not specified neither in the Holy Qur’an nor in the Sunna. Another evidence that they provide is what is narrated by Anas Ibn Malik. He said: “When the Messenger of Allah went on a journey of three miles or three leagues (Farsakh) (three leagues equal 26-30 km), he used to pray two Rak’at.”
Therefore, you are allowed to shorten your prayers depending on the opinion of some scholars, and you are not allowed to, according to the opinion of the majority of scholars. It is better not to shorten the prayer if the distance you cover is shorter than the distance which was specified by the majority of scholars.” This answer was given by Shaik Muhammad Ahmad Hussain to the one who asked him. 
Therefore, as the distance between Gaza and Jerusalem is almost 97 km going and 97 km coming back which is longer than the determined distance, you can combine and shorten prayers.