The usual term is vital status or living status. In a simple form or database field, you can also just use Alive/Deceased or Living/Deceased.

Best wording

  • Vital status : the most formal/clinical term.
  • Living status : clear and plain-English.
  • Alive or deceased : best if you want the field to be immediately understandable.

Example

A form might label the field as:

html

Vital status: Alive / Deceased

If you want, I can also give you the best term for a medical form , database field , or legal document.