There was a big study the EU commissioned to show negative effects of piracy on sales of various media. When it concluded that there's no negative impact, the EU decided not to release it. The only exception in the study were recent big movie releases, which did see significant (about 5%) financial losses due to piracy.

Link: https://www.engadget.com/2017-09-22-eu-suppressed-study-piracy-no-sales-impact.html

In 2016, the Technology Policy Institute looked at 25 piracy-related studies to analyze the combined data. According to them, there was a negative effect shown in 22 out of 25 studies. However, they also noted that it's a very complex question, and that the results were 'economic theory inconclusive'.

Link: https://techpolicyinstitute.org/publications/intellectual-property/copyright-and-piracy/the-truth-about-piracy/

When you take a look at these studies, you will very quickly notice a trend. They're always published by big, very much pro-copyright corporations. They use vague terms and employ questionable methodology.

A study showing a positive impact of piracy on video game sales (but negative for music). Music and movies seem to be the most likely to actually suffer from piracy.

Link: https://www.researchgate.net/publication/288206476_The_impact_of_piracy_on_physical_purchases_and_pay-downloads_A_comparison_of_four_cultural_industries

While it may be difficult to gauge whether piracy is overall beneficial or harmful to any industry, it seems to be quite clear that for video games specifically, it does not present any threat to sales.

Bonus: several successful studios are getting closed, and others will face layoffs. Because it literally doesn't make a difference how well a game performs. If it's a big corporation - layoffs will continue happening.

Link: https://gamesbeat.com/cwa-represented-workers-at-xbox-criticize-microsoft-management-and-pending-layoffs/