Single socket EPYC supports up to 128 PCIe lanes, does this meant that I can connect 128 x1 PCIe devices to a single socket EPYC system?

Every EPYC CPU has four dies, and every die includes two PCIe 3.0 x16 links. Each PCIe 3.0 x16 link can be bifurcated as you'd like for up to 8 PCIe device maximum per link. That means that each EPYC CPU can support up to 64 PCIe device in total.