There are very few ways George's Christmas Story could influence Spiderman Far From Home. One possible aspect could be in the area of character values. If George's story has strong moral values like kindness and selflessness, it could be argued that similar values are also important in Spiderman Far From Home. However, this is a very tenuous connection given the vast differences between the two. The movie is mainly about a superhero's journey, while the Christmas story is likely about the holiday spirit.
It's hard to see a direct influence. Spiderman Far From Home is based on the Marvel superhero universe and has its own set of rules and storylines. George's Christmas Story, which is likely more about Christmas - related themes, doesn't seem to have much in common with the world of Spiderman. Maybe the only influence could be in terms of character growth and moral lessons, if we really stretch it.