By the way of real-world comparison, Veliky Novgorod, the leading city of the Novgorod Republic, was at its largest just 5,300 households. The reasons for complaining over the size of in-game Novigrad have long escaped me.
5,300 households is still quite a lot. Assuming no more than a couple and one child per household - a modest estimation in my opinion - that's still a city of over 16,000 souls, which is quite a lot - though probably much, much less than canon-Novigrad would be.
Obviously, because of how video games work, you can't possibly have an actual capital-sized city in a game, unless you make your entire game setting about the city. I mean, even assuming Novigrad is "only" 50-100 thousand strong, that would make it a huge city, and gameplay-wise, navigating through it would be a HUGE p.i.t.a. The whole art here is to make you
feel like you're in a large, bustling city, without wasting your time with its most mundane annoyances, such as getting from point A to point B.
Say the burgomeister asks you to go see the captain of the guard for a certain problem : you want to get there. However, in life-sized city, that would take forever on foot... Take Paris: going on foot from what would be Town Hall to the equivalent of the Guards' Tower is about 1h20 if you're a steady walker.
Now, in a video game, you can get away with that by designing a "huge" city, but keeping everything important in a single bloc. It's easy to explain lorewise too: the guards' tower is right next to town hall both to protect it and to make communicating easier. Add in some sprawling background art and you've got a metropolis!
TL;DR: Novigrad - or any other city in TW3 - doesn't need to be big. It needs to
look big,
feel big, but stay small enough that we don't waste precious gaming time running around for no reason.