Does the gender of the evaluators affect PGR results?

No.  In the various studies of prior iterations of the report, no gender effect has ever been found.  I would be surprised if that were different this time.  Some areas of specialization do affect the overall results (e.g., those who do 20th-century Continental or philosophy of language tend to overvalue those areas in doing the overall assessments).  Despite that, in every past iteration of the PGR, and I am pretty sure in this new one (2017-18) too, women are invited to be evaluators at a higher rate than men (relative to their numbers in the profession).  Although I do not know the results for this year, I do know that in past years, women tended to decline the invitation at a slightly higher rate than men.