Hello eugenep
You probably mean the Gotthard Panorama Express. Yes, the Swiss Half Fare Card is valid. But, you need a 1st class ticket.
Alternatively, you could ride the Treno Gottardo, a regular train service serving the same line as the Gotthard Panorama Express, yet no reservation fee and no documentary / travel guide.
https://www.sbb.ch/en/leisure-holidays/trains-boats/panorama-trains/gotthard-panorama-express.html
https://unterwegs.sob.ch/de/stories/gourmet
The resident’s Half Fare Card and the tourist’s Swiss Half Fare Card do have the same range of validity. Where ever Half Fare Card is mentioned, it also applied to Swiss Half Fare Card.
Kind regards,
Roland