Yes. By 1980, Star Wars fans were told that George Lucas originally intended to shoot a series of nine movies, three in present of Star Wars, three in its past, and three in its future. In many interviews done around the time of the original film's release, Lucas said simply that he planned on making a series of Star Wars films, even if the first film was not successful. He did not name the number, but he would fund the sequels himself and, if necessary, he would shoot them as much smaller, cheaper films. By 1978, however, Time magazine confirmed that sequels were being planned and reported as many as twelve films total, and The Empire Strikes Back producer Gary Kurtz was quoted as saying there were as many as five planned Star Wars sequels. By 1979, Lucas confirmed in interviews on the set of Empire that a total of nine films (a trilogy of a trilogies) were planned: "The first Star Wars movie was one of six original stories I had written in the form of two trilogies. After the success of Star Wars, I added another trilogy. So now there are nine stories. The original two trilogies were conceived of as six films of which the first film was number four." Also around this time, actor Mark Hamill was quoted as saying that Lucas had told him he wanted to shoot the later sequels when Luke Skywalker was Obi-Wan Kenobi's age.
Many other people involved in the making of Empire also stated that Lucas had planned a nine-part saga, with the original Star Wars trilogy being the middle trilogy (this is also stated in the liner notes for The Empire Strikes Back soundtrack album). So by 1979, fans knew that Lucas planned to shoot a trilogy of Star Wars films and that he had another six planned after that. Lucas continued to talk about Episodes VII through IX, in interviews throughout the 1980s and '90s; however in 1999, he started back-pedaling, saying, "I'd always envisioned it as six movies", and in 2001, "the idea of a third trilogy was more of a media thing than it was me."