Does every ninja become a jonin? In Naruto, a number of ninjas have become jonin, such as Neji and Kakashi. Does every ninja who becomes a chunin by definition become a jonin if they live long enough, or do some remain a chunin forever?
No not everyone will become a Jonin. As you may have noticed, some ninja like Naruto don't even become Chuunin. Naruto is a rare example however.

In order to become a jonin, a ninja must be extremely skilled. Jōnin are generally able to use at least two types of elemental chakra, some genjutsu, and above average taijutsu skills.

They are usually also appointed to A and/or S ranked missions alone while those under the Jonin rank usually go with a team, or not at all.