I was thinking of buying a ryzen 3800x but I dont know what gpu to buy with it. I was thinking about a rtx 2070. Is there a certain stat in the gpu that I should look at that matches with the processor? (For it not to bottleneck)
That cpu will not bottleneck any gpu on the market. You can run a 2080ti or any top tier gpu for the next 2 generations. Games are taking better advantage of multi-core processors, so the 3800x will be a great cpu for many years to come. Get whatever gpu your budget allows.