How many years do you have to stay in college to become an engineer?

It depends on the program.

If you have a co-op program, then you are going to take about 5 years to complete your degree. Note that most students fail at least one course. For some courses, the failure rate is as high as 70%. (Obviously, you can retake the course later.) If you fail courses, you will, of course, take longer to complete your program.

After graduation, you may require an "internship" for several years before you qualify as a "Professional Engineer". For example, most jurisdictions in Canada require a Bachelor's Degree, Canadian Citizenship, 4+ years of relevant job experience, a written Professional Practice exam, and references from existing Professional Engineers.

If I might make a suggestion - if you are considering taking Engineering for the money, a trade is more lucrative in both the short and long term.