Alex,
This post should answer your questions:
https://airlinepilot.life/t/how-much-does-a-flight-instructor-earn/8061?source_topic_id=11451
Pay is based on how many hours flown, how many sim lessons conducted, how
many written exams proctored, and how many hours you have when you
interview to receive Tuition Reimbursement.
A CFI’s student load will fluctuate. No one can guarantee you a fixed
salary. Some months you will make less, other months more. My suggestion is
to look at the pay scales in the link above and take the average. Making
ends meet as a CFI can be hard. Sometimes sacrifices have to be made. If
you’re planning on taking out a loan, asking the bank for more money on top
of tuition costs to cover living expenses is always an option.
Tory