I have spawned over 100 peds ingame before. You have to modify not only lua code to achieve this...but also edit the .dat files inside of trigger.img.
Trigger.img hard locks ped counts...especially in freeroam. I can explain how to do this in another thread if you like.
I found this on trigger.img, the "population.dat"
and there is a code like this in that population.dat
TOTAL 15
PREFECT 0
NERD 0
JOCK 0
DROPOUT 0
GREASER 0
PREPPY 0
STUDENT 0
COP 1
TEACHER 0
TOWNPERSON 14
SHOPKEEP 0
BULLY 0
for setting 100 peds, do I just need to make the "TOTAL" to 100?
and set all the other like PREFECT, NERD, JOCK, ans etc into the total count of 100
is that it? do you mind to teach me about this?