I was told yesturday that my xray shoeed i had arthritis in, my c7 in the neck at my age how likely is it that it is osteo and not something autoimmun?

Likely degenerative: For a 33 y/o to have localized osteoarthritis at one cervical level, it is probably the result of one or a series of injuries that have occurred over time. Unless you can recall one major issues years ago, it is not uncommon for degenerative changes in the cervical spine to at times be called "normal changes" since almost everyone will develop degenerative changes in the neck over time.

Lab work : Osteoarthritis would be more common, even at your young age. If you don't have symptoms if inflammatory arthritis such as pain and swelling in other joints, it probably is osteoarthritis. One way to pursue it if you wanted to would be to undergo blood tests to rule out the inflammatory types of arthritis.