What is the authenticity of the Hadith: "And that you are sustained by 'Subhan Allah wa bihamdihi' (Glorified is Allah and praised be He), or were it not for 'Subhan Allah wa bihamdihi', you would not be sustained"?

There is no hadith (definition) with this wording. Perhaps the questioner is referring to Noah's وصية (counsel/bequest) to his son, in which it states: "I command you with two things..." The second command was: "Say 'Subhan Allah wa bihamdihi' (Glory be to Allah and praise be to Him), for it is the prayer of everything, and by it, creation is provided for." Narrated by Ahmad and Al-Bukhari in Al-Adab Al-Mufrad, and authenticated by Al-Albani and Al-Arna'ut.