From the world he comes from, they can calculate approximate yield per plant based on grow conditions-indoor/outdoor, lighting, soil, temp, etc. They won’t know exact yield prior to first harvest, but there is a measurable baseline based on previous recorded conditions and a measurable “standard.” He would have been better reaching out to tobacco farmers though. Not sure many people here are farming tobacco. Mostly end users. It’s like asking a car forum what the production capacity of vehicles coming from a Ford assembly line is based on raw material numbers.