Forgive me if this is weeks out of date, but (ahem):
The episode is called "The Deal," #14 in the series and one of my all-time favorites. Save this one when it comes out in syndication, it's a classic. And I've seen all but about six of 'em.
The poem's title I don't know, but the author is Yeats, not Keats. William Butler Yeats was an Irish poet of the early 20th century, while John Keats was an English poet of the mid-19th century. Both great poets, but VERY different.
Just another recovering English major showing off.