I have not had a scheduled day off for the past 2 1/2 years, the only
days I have had off are vacation days and a few that I requested, and when
I requested a day off I was made to feel like they were doing me some big favor.

I work 50+ hours every week with no overtime because they have me as
salary even though I have no one working under me.

What are the NJ laws concerning this? Am I eligible to some type of compensation?

Thank you,
Notimeoff

If you are salaried, you are stuck. But the approach to this may be thru health and safety and occupational safety laws.
http://www.state.nj.us/labor/lsse/lsonsite.html
http://www.state.nj.us/labor/lsse/lsnjsisc.html
http://www.state.nj.us/labor/lsse/lsgenfaq.html
You may want to get your place of emplyoment set up for a visit and audit.