Silica Gel in small amounts should not harm your dog or kill your dog.
However if the dog did eat a bit of Silica Gel or a small packet of Silica Gel then the dog could suffer from gastrointestinal issues.
And the main health risk for dogs who eat Silica Gel packets is the packet itself that can cause an intestine obstruction which could be potentially fatal for the dog.
The Silica Gel is not toxic itself but it can also dehydrate the dog or it may have absorbed other toxins such as through medicine or other things that the Silica Gel was protecting.
If your dog did eat a Silica Gel packet you might want to at least call the vet to find out what they would want you to do.
Sometimes it might be best to bring the dog into the vet and other times the dog will be just fine.