I lived in Cairo-Egypt for three years between 2007 and 2010, right before the ousting of Mubarak. I lived in Israel for eight months, and in Jordan for a year. I studied Islam and learned some Arabic. The vast majority of Muslims believe "Jahannam" (جهنم) is eternal, forever, for non-Muslims. There are Muslims who will go to hell, but for them it's more like purgatory. The Sirat (سراط) bridge that extends over the fires of hell will not successfully be crossed by many Muslims and they will fall into the fire, where they will remain for a certain period of time. But if you ask most Muslims if they believe hell is eternal or forever, for people who reject Muhammad as their prophet, they will answer in the affirmative. Yes.
After death we go to "Barzakh" (بَرْزَخ), which is the state of the grave. This is a very Hebraic, biblical view, not found in modern, rabbinic Judaism or Christianity. The concept of an intermediary, underworld, between life in this world and the day of resurrection. This is the original, ancient view of death by the original Hebrews. It wasn't exactly as described by Muslims, but it is very similar.
In death we enter the state of the grave, we go to "sheol", where we are mostly in a state of slumber, weakness, faintness. The wicked are in a nightmarish state, tormented by their own dark, evil thoughts and deeds, and a sense of impending divine judgment and destruction. They know they're doomed. The righteous however, are in a restful, peaceful, dreamlike state looking forward to their meeting with YHWH and His angels, in the day of judgment. Their lives were committed to YHWH and their good deeds (their conscience) remind them of their final abode in paradise, in the Kingdom of their Creator. That's the ancient Hebrew view of death, similar to the Muslim's concept of Barzakh.
