Do you know the species? Photos of your tank may help. If this is a large egg species (bimaculoides, mercatoris, briareus), you may be able to raise a few. We have not seen success with small, planktonic at birth species (vulgaris, hummelincki, GPO, aculeatus, rubescens).
Sadly, there is little known advice to be had but we always encourage any attempts keepers are willing to try. A very, very few successes by large aquariums have been accomplished feeding live crab zoeae but obtaining new hatched crabs is almost impossible. Assuming these are a tiny pelagic species, they live in the water column for about a month (time varies with species) and eat planktonic animals. You can try any tiny crustaceans you can find but most available items are frozen and haven't shown success (other than new hatched crabs). Brine shrimp have had no success with any cephs. They may attack each other and any meat eating corals and/or fish in your tank will consider them food. You might try separating a few and experimenting if you have a second aquarium.
There is a thread in the Octopus care forum, Raising Octopus Hatchlings Links containing links to information we have gathered as well as links to threads of others who have journaled their attempts.
Is the mother in the tank and still alive? She will not pose a predatory danger to her offspring but will not survive very long after all the eggs have hatched so you will want to watch her carefully so as not to poison the tank when she dies.
they r doing fine atm i feed them kent phytoplankton they swarm in a ball maybe there are eating so hard to see them only with jewelers eye atm,will see how it goes um i have a brinshrip hatchery on the way u say that they dont eat them what about ReefPods Tisbe ?
Like cuttlefish hatchlings, octopus new hatch may eat brine shrimp but there is not enough nutrition (even if gut loaded/coated) to keep them alive. Any other kind of small crustacean is worth trying. Do read through the prior experienced linked in the thread I provided above (the name is a link) for some ideas and expectations. The pelagic hatchlings can survive for 2 - 14 days without eating. The longest survival with feeding that I remember is 21 days.
It is interesting and unusual that she is eating, encourage her. I kept a mercatoris (Trapper - Caribbean dwarf, a large egg species) that ate through most of her brooding and would take Cyclop-eeze (no longer available) after hatching. She lived 12 more weeks but this is very rare for the animals we typically keep, less than a week is typical. There are two, related, West Coast Pacific species that have multiple broods but we know of no other that survive a hatching event.