Gamers is a hobby shop specializing in anime, manga, games and their related merchandises.
AKIHABARA GAMERS - Image courtesy of Japanese Wikipedia
Apparently, Gamers has appeared many times on Love Live! anime. According to NineColors.com (Japanese), a site that lists real-life places used in the anime:
When comparing to other shops, only Gamers have its original name shown with proper logo while others were changed. This gives a big hint that it's a product placement deal.
However, Gamers itself has done some tie-ups/collaborations with Love Live! series itself. Some examples are bonus merchandise for Love Live! products (anime Blu-Ray, CD singles).
According to オタクの戯言's HatenaBlog (Japanese), there's also a special booth for "μ's Final Love Live!", displaying the outfit used on "SUNNY DAY SONG" performance and other things like visitors' comment, merchandises, all released singles and albums, and posters.
Moving to Love Live! Sunshine!!, there's Gamers Museum, displaying a comment board (separated into text only/with picture), Aquors scene in the anime, introduction to their songs, and casts' signature.
Last but not least are Love Live! Sunshine!! special pages on Gamers (Japanese) and Gamers onlineshop (Japanese) website.