It does, but you are only talking about a few FPS difference, especially with a single GPU. Games also respond differently as well between the two versions. With SLI or Crossfire, the difference is a little more, but still not that much more. Here's a five year old review of that with GTX 680 and Radeon 7970 GPUs in single, dual, and triple cards showing the differences: https://www.hardocp.com/article/2012/07/18/pci_express_20_vs_30_gpu_gaming_performance_review/2
Long story short, if bandwidth of the GPU is stretched, it will make a bigger impact.