I agree that he does die, and one should not overlook the parallels to Harvey's cold and lonely death to that of his victim's, Susie Salmon.
Harvey had lured Susie to an underground "hole" in a frozen cornfield. He will meet his death also in the bitter tempertures, in a "hole" as well (the ravine), and the shape of a the icicle that kills him is similar to the shape of a corn cob.
Also, like Susie, no one knows where he is and it will be some time, if ever, before he is found.
Yes, he does die. At the very end of the book, Harvey falls into a ravine (a narrow gully with steep sides) after he's hit by the falling icicle,and snow covers his body. This can only mean that even if he survived the fall, no one will find his body because it will be concealed by the snow. It would also be hard to spot down in the ravine.
I saw the movie yesterday. And by the fall I'd reckon anyone would die instantly!