Symbolism, Imagery, Allegory
In addition to "The Overcoat," Nikolai Gogol is known for the novel Dead Souls (check out the full text). Instead of going in depth, we'll just tell you, very briefly, that the story takes place in Russia before the emancipation of the serfs in 1861. Back then, landowners could claim serfs, or "souls," as property. The novel follows one unscrupulous guy who attempts to buy up dead souls – serfs who have died but are still on the property registry of the landowners – in a convoluted plan to make a lot of money. Gogol's novel toys with the ways in which people can have an existence beyond death (even if it's for tacky, money grubbing purposes).
The Namesake is also obsessed with birth, death, and rebirth. In the novel, births do not occur just at the beginning of your life, when you are assigned a name, but can recur throughout your life at important times when your identity undergoes a stark transformation. When Gogol officially changes his name to Nikhil, he's a little bummed that there's no one to celebrate this day with him – specifically, with Polaroids and balloons, the stuff his family brings out for birthdays. Ashoke feels like he got a second chance at life when he survived the devastating train wreck in 1961, and Ashima compares living in the United States to an extended pregnancy.
We also see this motif of the "dead soul" in the way the Gangulis relate to their families back in India. Because of the great distance between them, their existence is reduced to a voice on the telephone, or some words on a letter that always arrives too late. They are not fully, physically present to their relatives; instead, they are like ghosts, who exist, but only in memory. Letters and photographs become especially significant because they preserve a loved one's existence even when the loved one is distant – or dead, as in the case of Ashoke.
Similarly, Gogol is haunted by his father's presence, particularly when his father dies. Ashoke's presence continues to haunt Gogol through his name, which is closely tied with Ashoke's first brush with death, and his rebirth in America.