Arista does run software on their switches. But that is the supervisor, aka the control plane. The data plane, where the actual throughput is achieved, is done

Arista does run software on their switches. But that is the supervisor, aka the control plane. The data plane, where the actual throughput is achieved, is done with ASICs, and in some cases where user programmability is needed, FPGAs. At no point does Linux handle 1 Gbps+ traffic in those switches.