Can a smoke detector circuit be GFCI and CAFCI protected?
A smoke alarm can be AFCI and or GFCI protected so the answer is yes. Code  exempts fire alarm systems installed to code NEC 210.12.A.6. from AFIC requirements. My state also exempts Fire alarms from GFCI requirements.
  The risk to the system tripping out is greater than the chance of a fire or shock from the system. I totally agree with @Harpers comment.