Grays can only come from ONE gray parent. If the parents are both grays, baby will be solid. If baby stays solid, it will NOT pass the gray gene. This baby looks like it will definitely go gray, and you may notice some dappling. Because she's a bay starting out, chances point out that she'll be a reddish gray, either with some lighter/white dappling, or darker black dappling.
I noticed that she has a white stocking? Are there any black spots on her coronet band? (Hairline above her hoof)
That isn't accurate.
There is both hetero and homo carriers for the gray gene, which means that the foal can recieve the gene from both parents.
Only gray horses carry the gene, thus 2 gray parents can sire a gray foal. That is the only way to get a homo gray carrier.
Solid horse cannot sire gray and does not carry the gray gene.