No, it isn't a parsing engine, it's purely a statistics based engine. What it generates is based on patterns found in the text that was fed to it. It doesn't comprehend what it generates or the meanings of the words it outputs, all it understands is the statistical relationships between words. i.e. GPT ends a sentence when statistics say that the sentence it's constructing is not usually that long. It ends a sentence with a word or phrase that's statistically found at the end of sentences.