The Owl-Eyed Man is similar to the billboard for Dr. T. J. Eckleburg with the "all-seeing" eyes. Both symbolize an uninvolved, spectator god. They watch all the activities of the humans struggling below, but don't comment on them or try to correct wrongs or lessen burdens. While Owl-Eyes does make a comment about Gatsby's real books earlier in the novel, he still provides Nick with no advice or significant knowledge about Gatsby. He simply makes his observation and leaves it up to Nick to draw his own conclusions.
His presence as one of the few people who actually attend Gatsby's funeral could demonstrate "God's" watching when humans are put to rest or could mean that in all his observing of Gatsby, he at least thought that Gatsby was worthy of his presence at his burial.
The owl-eyed man is an observer, someone whose clear-sightedness allows him to see Gatsby for who he really is. We first meet him in chapter three: He claims to have been drunk "for about a week," and he looks at Gatsby's library in astonishment:
“Absolutely real — have pages and everything. I thought they’d be a nice durable cardboard. Matter of fact, they’re absolutely real. Pages and — Here! Lemme show you.”
Taking our scepticism for granted, he rushed to the bookcases and returned with Volume One of the “Stoddard Lectures.”
“See!” he cried triumphantly. “It’s a bona-fide piece of printed matter. It fooled me. This fella’s a regular Belasco. It’s a triumph. What thoroughness! What realism! Knew when to stop, too — didn't cut the pages."
David Belasco was a famous Broadway producer, known for the realism of his stage sets. The owl-eyed man correctly sees Gatsby's house, and his party, and possibly his guests (Nick included?) as stage props.
When he comes to Gatsby's funeral, he says a few words to Nick:
We straggled down quickly through the rain to the cars. Owl-eyes spoke to me by the gate.
“I couldn’t get to the house,” he remarked.
“Neither could anybody else.”
“Go on!” He started. “Why, my God! they used to go there by the hundreds.”
The owl-eyed man's sympathetic feelings for Gatsby are a little confusing if we think of him as impartial. I think far from being impartial, the owl-eyed man is maybe the only character in the book who is able to fully empathize with Gatsby. His appearance at the funeral allows Fitzgerald to give his pithiest assessment of Gatsby's career ever:
He took off his glasses and wiped them again, outside and in. “The poor son-of-a-bitch,” he said.”
The owl is seen as an all knowing animal. They are thought of as very intelligent. Owls are symbols of wisdom and great sight. Some people see owls as an omen of death.
Fitzgerald had the owl eyed man show up at Gatsby's funeral for a couple of reasons. When we first see the owl eyed man, is at the party Gatsby has thrown and invited Nick to. The man is surprised when he realizes Gatsby's books are real books. This shows us that the man in intelligent and just thought that Gatsby was very superficial. So many people showed up at these parties and enjoyed Gatsby's wealth. They had no problem taking advantage of him. As long as he was throwing parties and spending money, people flocked around him. When he dies, Nick has a hard time finding anyone to come to the funeral. Tom and Daisy have gone on a trip. Gatsby's father comes to the funeral. His father, Nick and the owl eyed man are there. There are also a few servants that have shown up. It is a great symbol of the character of the people in town. They completely took advantage of Gatsby and didn't even care when he died.
It is very interesting that the owl eyed man is the only one from the parties, that shows up. He saw the real person that Gatsby was. He was there to pay his respects to the man, not the one everyone wanted. Fitzgerald had the owl eyed man at the funeral, because he was the only one in this society that saw the real Gatsby.