Aug 9 (Reuters) - AMC Entertainment, the cinema operator beat second-quarter revenue estimates on Monday, lifted by millions of moviegoers at its theaters catching up on in-person entertainment after a year of staying indoors. Revenue at the company, one of the “meme stocks” at the center of a boom in small-time investing this year, rose to $444.7 million in the quarter ended June 30, from $18.9 million a year earlier. Analysts on average had expected revenue of $382.1 million, according to IBES data from Refinitiv. Reporting by Eva Mathews and Tiyashi Datta in Bengaluru; Editing by Maju Samuel Our Standards: The Thomson Reuters Trust Principles.