So I have a father that I met one time when I was 16.hes not on my birth certificate ,I'm 43 now I wrote a letter to him and no response that was 3 years ago.my question is can I make him take a dna test? and am I entitled to anything if he passes away?

There is really no way at this point to get a DNA test. If you can get anything from his estate if he dies depends on too many things.
1. where you are located, what country
a. if the US what state
2. If he has a will, there will be ways to write you out of course if he wants to.
3. how property is owned and transferred at death.