Depends on how strong you want each gummy, and how strong your Kief is.
Lets say you have high quality kief at 50% THC, and you want each gummy to be 25mg THC:
19grams = 19,000 mg
= 9500mg THC
9500mg / 25mg = 380 gummies.
So if you wanted 100 gummies at 25mg each,
= 2500mg of THC,
=5000mg (5 grams) Kief.