Yes, when accompanied by their parent/guardian. In general, your kids can stay in an Irish pub until 9pm.
Children (anyone under the age of 18) are only allowed in licensed premises if they are with a parent or guardian. This provision carries certain restrictions. For example, if accompanied by a parent/guardian, the child may remain on the premises from 10:30am – 9pm in the months of October to April (until 10pm May to September). The pub licence holder has the right to contravene this if he/she sees fit.
Children aged 15-17 years old may remain in pubs after 9pm where they are attending a private function at which a substantial meal is served.
These are the official guidelines. You may find the rules are not strictly enforced everywhere in Ireland.