Mr. Harvey's unusual death—stumbling into an icy ravine after being hit by a falling icicle—is deeply symbolic. Harvey has gotten away with all the terrible crimes he's committed over the years, never facing justice for his multiple acts of rape and murder. But the natural world has exacted its own justice on him. Mere human justice may not have been able to catch up with him, but natural justice most certainly has. And just as nature is responsible for the righteous death of a sadistic sex predator, it also gives Susie a kind of rebirth in the form of her new-born niece, Abigail Susanne. The endless natural cycle of birth and death has delivered its own unique form of justice, a higher justice that transcends whatever moral or legal justice system human beings could possibly devise.

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.