You can respond positively here and still hedge your bet. The attitude of "The Show Must Go On" is perfectly reasonable, but you can still circulate your resum

You can respond positively here and still hedge your bet. The attitude of "The Show Must Go On" is perfectly reasonable, but you can still circulate your resume and take steps to avoid burnout. You can even ask a potential opportunity if they will be interested if you do your best to save the other company and join later. But you need to be grounded in reality.