Fred Pohl, in a 1978 discussion with Alfred Bester (transcribed and posted recently here):
“No woman writer has been in any way handicapped by being female in science fiction in the last 10 to 15 years, with one single exception.”
Pohl, with his career as writer, agent, and editor, was in a better position to have an opinion than most people. On the other hand, as a male insider, he was in a better position to harbor self-serving delusions than most people. Also, his statement doesn’t address any possible prejudices harbored by the readers; even if the publishing chain was completely sex-blind, it would take account of how things sold, and so if the readers cared, it would end up being reflected in publishing.