Poe often revised and reprinted his works to purposefully improve them and expand his audience. Other times, his works were reprinted without his permission, thanks to the piracy-laden culture of reprinting in American publishing (in some cases, publishers would sell the works to other publishers, without checking with the writer). One example of this is the August 3, 1844 issue of the New World in New York, which reprinted the tale "Mesmeric Revelation," likely without Poe's authorization.
But, what prompted them to republish the work was not so much getting attention thanks to Poe's name, but the inherent interest of the story. The editor wrote: "Mr. Poe cannot, on so serious a subject, trifle with his readers: yet more extraordinary statements can hardly be conceived... we recommend it [e.g. the tale] to the perusal of our readers and invite them to draw their own conclusions."
Poe's story was being republished because it was believed to be a true account.
"Mesmeric Revelation" features a a mesmerist ("animal magnetism," as developed by Franz Mesmer, believed that the fluids in the body could be manipulated with magnets, allowing for a trance-like state similar to hypnotism) who wants to determine if the soul can survive after death. The mesmerist, coyly named "Mr. P.," puts Mr. Vankirk into a "mesmeric sleep." While in this trance, Vankirk and the mesmerist engage in a metaphysical discussion touching upon topics like the true nature of God ("What then is God?" Vankirk's answer is, "I cannot tell."). Vankirk dies while in this trance (much like Poe's similar, more horrific story, "The Facts in the Case of M. Valdemar") and, though Mr. P. tries to bring him back, Vankirk refuses because of his experience and "keenly redefined perception" from transitioning to what is, in essence, the afterlife.
The German-born Franz Mesmer introduced his process in the 1770s, making public spectacles of his discoveries, sometimes accompanied by a glass armonica, a musical instrument developed by Benjamin Franklin. Mesmer died in 1815, but his animal magnetism (he apparently never used the term "mesmerism") lived on, particularly through a traveling practitioner named Charles Lafontaine. In the 1840s, Scottish physician James Braid saw Lafontaine and developed a similar process which earned the name "hypnosis."
"Mesmeric Revelation" was republished several more times in the next few months. One reader responded that the story was likely true, but the "revelations" of Mr. Vankirk were hallucinations. One notable reprint was in the American Phrenological Journal in 1845. That journal, purportedly a one of science rather than literature, noted their belief in the story, though they were not attempting to convince readers. As they introduced: "We simply lay it before our readers, soliciting that they do by it as we have done, think it over fully, and form their own conclusions... Read and re-read." The editors later published a retraction.
Certainly, Poe's story made a stir (to his amusement). We can only speculate if Poe truly believed in mesmerism. The first lines of the "Mesmeric Revelation" are curious: "Whatever doubt may still envelop the rationale of mesmerism, its startling facts are now almost universally admitted." I would argue that Poe was, as he often did, appealing to the interests of his reading audience, rather than showing his personal interests. His italics on the term "facts" in that quote may be the hint...