How Will An Unborn Baby Gorilla Get Its Food?

An unborn baby gorilla, like its unborn human counterparts or the unborn babies of other expecting animals, gets its nourishment directly from whatever its mother consumes during the period of pregnancy. So usually, it obtains its food from the predominantly herbivorous diet its mother eats during the eight to nine-and-a-half month-period of her pregnancy. This mainly comprises a daily average diet of about 27 kilograms of food, which primarily consists of the barks of trees, buds, fruits and leaves.

A mother gorilla also gets her daily quota of water (which is necessary for her and is replenished every day) through these plant parts, so she does not necessarily need to drink more water or feed her unborn baby with more food than its tiny and underdeveloped digestive system can handle.

Pregnant gorillas usually feed themselves in two sessions during the daytime, namely in the morning and in the late afternoon before it gets dark. They catch up on their sleep between these two sessions of feeding and then build their nests of leaves and grasses.

My guess is the Mom Gorilla has an umbilical cord just the same way a Mom person would

I'm not sure if the answer given by "aki" is what you want to know (but it's a very good answer).  An unborn gorilla gets its nourishment in the same way other mammals do.  It gets it from the mother through the umbical chord.