If he streams or creates gaming content then gifts that support that are perfect. A green screen or ring light. Capture card or microphone. Overlays or emotes for his community. Channel membership or support for streamers he watches. These gifts work because they either enable the creative side of gaming or support the community he is part of. Someone who games seriously often has a community around that so a gift that supports or improves that side makes sense. These are gifts that acknowledge gaming as more than just playing.