Cinema Blend posted some quotes from an interview they did with ILM visual effects artists Rogert Guyett and Pat Tubach about the inspiration behind Supreme Leader Snoke in The Force Awakens. Here's a quote from that interview:
"Imagine when you’re a kid or whatever, you go up and you stand in front of the Lincoln Memorial. And you see old Lincoln in a huge chair. There’s a certain quality about that. So, that was certainly sort of part of the inspiration for it all. But I think, hologram, you know? The idea really in that opening scene is sort of like, ‘What is going on here. Ok, it’s a hologram. Is he really this big?’ OK, once you figure out that it’s a hologram, of course it’s like, ‘Well how big is he?’"You can read more right here.