Assalaamu'alaykum and Ramadan mubarak
Hell will never be empty. Paradise too will never be empty. Those who are sent to both Hell and Paradise will abide there eternally, except Jahannamiyyin (these are muslims who due to their sins are sent to Hell until Allah allows them out, when He does, they will be taken out of Hell and bathed and entered into Paradise. The people of Paradise will call them Jahanammiyin)
Narrated Ibn `Umar:
The Prophet; said, "The people of Paradise will enter Paradise, and the people of the (Hell) Fire will enter the (Hell) Fire: then a call-maker will get up (and make an announcement) among them, 'O the people of the (Hell) Fire! No death anymore ! And O people of Paradise! No death (anymore) but Eternity." Sahih al Bukhari
Narrated `Imran bin Husain:
The Prophet (ﷺ) said, "Some people will be taken out of the Fire through the intercession of Muhammad they will enter Paradise and will be called Al-Jahannamiyin. Sahih al Bukhari
Narrated Anas ibn Malik:
The Prophet (ﷺ) said: My intercession will be for those of my people who have committed major sins. Sunan Abu Dawud
Narrated Abu Huraira:
Allah's Messenger (ﷺ) said, "For every Prophet there is one supplication which is definitely fulfilled by Allah, and I wish, if Allah will, to keep my (special) supplication as to intercede for my followers on the Day of Resurrection." Sahih al Bukhari
That Day, no intercession will benefit except [that of] one to whom the Most Merciful has given permission and has accepted his word. Taha 109