Portrait of the Artist, thus far, has been a novel about the language arts. We know that, since it's sort of autobiographical, and the title calls the main character an artist, Stephen will most likely end up as an author.
We can see the influence that literature has on him very early in the book.
It begins with the story Stephen's father tells him about... well, I'm not really sure, but it's certainly a story, and it presumably has some importance in Stephen's life, because Joyce takes the time to write about it. This first section also ends with a little rhyme told to him by Dante about apologizing and eye-picking, which seems to have worked itself into his brain.
As we learn more about Stephen, one thing becomes apparent: he's a nerd. Instead of playing sports, he just shuffles back and forth on the court, the "fellows" don't like him, and he's a good student. Maybe the idea is that he has to escape the depressing realities of his real life, I'm not sure, but as is often true of fictional nerds, he spends much of his life in his imagination. And, if his inspiration for his imagination isn't coming from real life, it's probably coming from the stories he consumes. We see evidence for this in the way he thinks about his own actions. In his mind, his life is all very dramatized. Like we mentioned in class, he compares his bravery in telling on the pandier, to the heroic acts of the men in historical tales.
 Each chapter has its own story arc, which I suspect is partly due to Stephen imposing the pattern he has observed in literature onto the events in his life. He puts himself in the position of a story's protagonist and seeks out a great resolution or revelation because that's what's supposed to happen. Nothing (not the kids cheering for the rector instead of him, or the fact that the chance encounter with a magical female figure isn't all that random or magical) can ruin his idea of these little happy endings. Stephen feels a deep, romantic connection between himself and Emma at the party, and when the night doesn't turn out like it ought to, he has to write the proper ending in a poem.
Stephen has also obviously thought harder about poetry than his classmates, because he picks the controversial Byron (obviously his own decision) as his favorite instead of a more popular poet. We can see that he really connects with Byron's emotionally laden, romantic style in the flowery language that is used in the book at this time, and the fact that he will soon deviate from the church for the sake of passion or love or maybe just rebellion. The poetry foundation describes Byron's hero as "defiant, melancholy, haunted by secret guilt", which is a good description of Stephen in this section of the novel.
And, after all this deviation, he doesn't feel guilty till he reads (emphasis on reads here) that his sin would offend the Virgin Mary, and that it might multiply into all the others. At which point, he becomes obsessed with the souls in purgatory, which are no more than abstractions to him, and so, in a sense, like the characters in a story. I dunno, the last ones are stretching it a bit, but I do think that stories have an unusually large effect on his development.