We can infer from this scrupulous tabulation of dates that Dickens was (at the very least) reminded of the tales during the time that Little Dorrit was gestating and that he probably re-read them, increasing the likelihood of The Fall of the House of Usher's having exerted some influence on that novel--a not-inconceivable line of influence, even though it reverses the usual arrows of the flow chart.
(As the Pilgrim editors remark, Poe owed much more to Dickens than vice versa, being "the first America n critic to see CD's true importance," using "him in his articles, from 1841, as a model by which to judge other writers," and almost certainly gaining "ideas from him ... for his own tales and poems" [3: 106n].) So far as I can tell, the motif of the collapsing house in Little Dorrit has not been traced to Poe's Fall of the House of Usher, though it seems an obvious enough comparison to draw.
One is struck throughout by the similarity of subject-matter, and, at the same time, by the differences of tone and