There are not too many (only one I know of) male octo species that actually give up their arms. Some, however, do give up their lives if the female is particularly hungry, ornery or just in a bad mood (we really don't know why some males are cannibalized and others of the same species are not). Yes, the female stores the sperm in both cases but the expected viability of the sperm is only about 3 (4 at the most) months.
If she is guarding the cave there is likely a larger clutch inside. You might try taking a video and then enlarging it to see if the camera can pickup more than your eyes (I have often found this to be helpful).
Your first sign of viability on the eggs will be black dots in the eggs so it will be helpful to try to take photos every few days if you can get an angle that shows an egg. These will be the beginnings of eyes.
