Does Find My Mac work if my mac is in stealth mode?

Yes if stealth mode is turned on find my Mac will work see some articles Use Find My Mac to locate a missing Mac - Apple Support

OS X: About the application firewall - Apple Support

Enable stealth mode

Enabling stealth mode prevents the computer from responding to probing requests. The computer still answers incoming requests for authorized apps. Unexpected requests, such as ICMP (ping) are ignored.

Firewall limitations

The application firewall is designed to work with Internet protocols most commonly used by applications – TCP and UDP. Firewall settings do not affect AppleTalk connections. The firewall may be set to block incoming ICMP "pings" by enabling Stealth Mode in Advanced Settings. Earlier ipfw technology is still accessible from the command line (in Terminal) and the application firewall does not overrule any rules set using ipfw. If ipfw blocks an incoming packet, the application firewall does not process it.