Since Snorri himself was a Christian, and his works are some of the most popular sources for Norse Mythology, is he to blame for the modern "Christianized" interpretation of Norse gods and beliefs?
Short answer: probably yes. He's our primary source for a lot of myths, which makes it hard to say our interpretations are accurate to what was believed a thousand plus years ago because we don't have anything to compare it to. He was Christian, and likely fudged/altered much of his recording of the myths to make them fit into the Christian worldview.(such as demonizing Loki or at least making him fit more the Christian role of an evil/demonic figure rather than the classic trickster figure he's more likely to be, the whole Ragnarok myth isn't actually recorded elsewhere, the idea of Heimdall becoming a Christ-like figure after Ragnarok, a man and a woman repopulating the world after the end of the world... there's a Lot.)
However, it's not all his fault, probably. He was writing several hundred years after Christianity became a major force in Iceland, so many of the myths may have changed already by the time Snorri was born. And the myths we know now are Norse myths are primarily just from Iceland, which had a lot more integration with Christianity than a lot of other Scandinavian countries, iirc. There are a lot of factors, but it's largely due to Snorri. It's a lot like basing all your knowledge of current world religions off a book aimed at teenagers on the subject.
I will say Snorri's works cannot be simply brushed off as fiction. There are countless stories of this type from several cultures, and they in many ways connect or resemble each other. So to count his stories as imagined or made up I believe is unfair. Although, I do not see how he could have had anything to do with influencing Christianity. Seeings how Christianity was born in AD 30-35. His accounts not even written until well after 1200's. So, as far as being the soul influencer is not even logical, in my opinion. I would also like to include the fact that the Catholic religion was far more of an influencer. The Roman Empire actually adopted Christianity as its religion in 380. This around the time Christianity separated from the Jewish background, which was where it began. Due to the newly founded doctrine at in motion, with help from the Roman Empire.
By the 1st century the religion had already began separating itself into sects, due to unlike ideals about Scripture. In 364-378 successor Theodosius made it legal that only those that followed Trinitarian Christianity would be considered, Christian Catholics. All others were considered heretics and their practices illegal. Docetism, was out to directly erase the ideal of the Nicene Creed. Wanting all to believe and honor their new Orthodox Christianity. Which, by the way, was completely created and established, merely due to what they told their followers the Scripture was saying, not actually what it said or depicted. Although the Roman Catholics adopted Christianity, they only adopted the name. Reason being that after the 4th century, there were numerous sects made for Christians. As they all had their own opinion on what the Scriptures depicted and what each sect deemed depicted, by the Scriptures. It wasn't until the begining of the Medieval Era, that they finally let it be known they were never really "Christian" they still used the term, but returned to Roman Catholic. And by 1120 they had left a trail of corruption and devastation, effecting multiple nations and countries. Persecuting relentlessly, anyone whom did not confirm and obey. I would have to say this would be a more satisfactory example of influence on Christianity.