WASHINGTON, Sept 20 (Reuters) - U.S. officials have not given up hope of landing a Gaza ceasefire and hostage deal but are increasingly pessimistic that a breakthrough can come anytime soon, according to sources and officials familiar with the matter. The Wall Street Journal on Thursday reported that senior U.S. officials were now privately acknowledging that an agreement may not be within reach before President Joe Biden's term ends in January. While noting the dim prospects, several U.S....