Imagine an intelligent being in a GoL board, made of a huge pattern of cells (just like we're made of a huge number of atoms).
Even though when we look at a GoL board, we know it's made up of cells and that everything operates according to a fixed number of rules, this intelligent being wouldn't just be able to know this. It's perceptual system would be made of these elements (perhaps it somehow uses spaceships to find out about what is out there). Remember that you can't just "see" reality - you need inputs and to infer what's out there on the basis of them. The sort of view of its reality it could infer would be much more coarsely grained than at the level of individual cells, just as our unaided view of reality is much more coarsely grained than the level of individual atoms.
That intelligent GoL being could observe the way things behave and, on the basis of this, theorise the GoL rules - that everything was a bunch of cells, and that if there's an empty cell and it has three neighbours then that cell will be 'on' in the next moment, and so forth.
And if it existed in a 'standard' Game of Life board, it would have theorised correctly. But if it lived in a Game of Life board where each of the cells it has posited is actually one of these unit cells like in the linked page, then there would be a deeper reality than it realises (and of course there could be 'deeper levels' within that).
There's no way that GoL being could tell.