The story of Jamal and Latika is Orpheus/Eurydice-like.
Boy-meets-girl, boy-loses-girl, etc.
Boyle's inclusion of one scene nails the story as THE Orpheus myth, and not just an archetypal resemblance.
One evening, Jamal and other thieves are stealing purses from an audience that is watching an operatic performance. Jamal takes a moment to watch the tenor singing his lament on stage. But just a moment. Danny Boyle cuts quickly from the operatic scene to a fleeting glimpse of Latika and then to the gameshow set, where Jamal must answer the next question on his way to 1-billion rupees.
Watch the clip. (A link is on my slide: OGCMA0797NOTOrpheusEurydice_Boyle. Click the "chapter 12" link right sidebar.
Did you catch the song the operatic tenor was singing? It's the moment in Gluck's Orfeo where Orpheus has just lost the love of his life, Eurydice.
Danny Boyle worked with Vikas Swarup's novel, Q & A (now retitled after the film Slumdog Millionaire), and introduced the element of Orpheus into the plot. Indeed, there is nothing of Orpheus/Eurydice except archetypal similarities in the novel itself. The insertion of overt Orpheus elements into the film is entirely the genius of Danny Boyle.
Swarup's lovestory has archetypal resemblance to Orpheus. Boyle's lovestory uses the Orpheus myth to add depth and new meaning to the narrative. The myth works like allusory shorthand.