Lets talk to Allah

The time period of disbelievers in Hell.

Indeed, hell is waiting in preparation for the transgressors (disobedient rejectors who oppose the messengers). They will abide therein for ages (eternity).  They did not believe that there would be an abode in which they would be taken to account. [MAY ALLAH TA'ALA PROTECT US]
There is this verse in the Quran 78:23

لَّٰبِثِينَ فِيهَآ أَحۡقَابًا

The word Ahqab, which is the plural of Huqub. Huqub means a period of time.

bn Jarir recorded this statement.

Ibn Jarir also recorded from Salim that he heard Al-Hasan being asked about Allah's statement,

"In reference to Ahqab, it has no specific amount of time other than its general meaning of eternity in the Hellfire. However, they have mentioned that the Huqb is seventy years, and every day of it is like one thousand years according to your reckoning (in this life)."

Ar-Rabi' bin Anas said,

"No one knows how much time this Ahqab is, except for Allah, the Mighty and Sublime. It has been mentioned to us that one Huqb is eighty years, and the year is three hundred and sixty days, and each day is equivalent to one thousand years according to your reckoning (in this life)."