Gogol is the hero of our tale. His complicated relationship with his name drives the entire story, and most of the story is told from his point of view. Most, not all.
The novel sometimes veers away from Gogol's point of view and spends some time with Ashima, who becomes the heroine of her own subplot. While Gogol's story explores the life of the children of immigrants, Ashima's story explores how immigrants themselves adapt to life in the United States.
Not to be outdone, Ashoke finds himself smack dab in the middle of his own subplot, and the novel spends some time telling the story from his perspective. Because of this, we can understand why he decides to come to America, why he names his son Gogol, and how he deals with changing family dynamics in his adopted country.