Agree with pyrotech.
Having worked in a soup room in a factory.
Some ingredients scale well and others don't. Red/Green peppers scaled generally 1:1 it was not uncommon to add 5#'s of powdered spices to 20 or so gallons. Chilies are an odd bird start with about 25% of scaled values and have the rest ready. Celery is generally safe to go 1:1, onions can go 1:1 early in cooking. Garlic early add 1:1, late add start small it adds a lot more flavor when added at the end of a cook. Tomatos 1:1 but watch acidity. Dried spices are a big one you have to watch, same with any beers or liquors as they rehydrate hot get hotter quickly or dilute in unexpedted ways. Wait 2 mins of good stiring before tasting again from a change as the spice will partially rehydrate.
Stir often and SCRAPE the bottom to make sure you are not burning the soup at the bottom this is both very easy and very common on huge batch cooks.
Any specific questions you can ask via PM but I haven't worked in the soup factory in 11 years and I only made it a year before I got promoted to componet and raw rooms.
You could make 10 small batches of little pots but the problem comes in when it ages. That is why you will want to stir and ladle a cup and see how it reconstitues and adjust from there for last min tweaks and taste thoughout the day to make sure that it still has fluids. (Line Cook at a restaraunt)
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