It cant be. A POP is a quantity of individuals needed to maintain a portion of empire (what porion, what maintain etc?) And we may guess how many this is
for example:
- Early space age, and atomic age primitives that is somewhere near rl earth in XXI which is around 7,5 billion people, has 26 pops, which translates to 1 pop being around 250 - 300 million humans.
Of course different species are different - some are larger, some has more hands to work, some eats much more, some are more fertile, and thus quantity of one POP is different for each species, but overall output from one POP remain the same, and this is a reason why we have not specific number but rather enigmatic "POP".
One can say that 1 billion ants could be as much efficient as 1 human. So if one pop would be 300 milion humans, then it would be 300 x billion x million ants, but its way easier to say for both "ONE POP".
And if crew of one starbase is around 1000 humans (i believe its much less), with one pop being 300 millions, then one should have 300k starbases to generate additional pop from them.