John Gill Commentary John 12:33

"But this he said, signifying by what manner of death he should die." — John 12:33 (ASV)

This he said
These are the words of the evangelist, interpreting the design of Christ in the above words, thereby

signifying what death he should die ;
the phrase of being lifted up from the earth, not only signified his death, but the kind, or manner of it, that it should be by crucifixion; a person crucified being stretched forth upon a cross, and that erected, was lifted up between earth and heaven.