In the sentence you provided, the author primarily employs ethos. Ethos refers to the credibility or ethical appeal of the speaker or writer, which is established through the use of evidence, such as the findings of a study. By referencing a "Fortune study," the author positions the argument in a manner that suggests authority and reliability, thereby enhancing the credibility of the claim about gender bias in performance reviews.
While there are elements of logos (logical reasoning) present in the use of empirical evidence, the focus on the study's findings aligns more closely with ethos as it seeks to establish credibility regarding the claim of a gender problem in journalism.