This is surprisingly hard to find a straight answer about.

Amazon itself does not advertise a maximum image size. They do, however, tell you the max size per layer in their service quota page, which is 52,000 MiB (or ~50GiB).

Other sources state 10TiB or 25TiB but those are unconfirmed by AWS.

Your mileage may vary with the TiB size range, but it's safe to say with a layer size limit is 50GiB, an 8GiB image should be fine.

However, your issue may be with the layer sizes themselves. From personal experience, I've seen more failures when layer sizes exceed 1GiB. Trying to keep layer sizes below 1GiB might be something you would want to try.