Depends on 2 adults and 4 kids or 4 adults and two kids. Anyone 10 and over pays adult prices.
You could estimate if they are all buffets $35 per adult average and $15 per kid. $170 for two adults two kids 10 and over and 2 younger.
About $30 per meal x 6 = $180 in tips
If the buffet is less or more it will even out. Or if you have four actual under 10 and two adults. Its a good estimate if you don't want to do meal by meal!
Enjoy your trip. If your meals are less expensive you'll have some extra money. You can put on a Disney Gift Card and call it your tip card.
I had issues because they bring the card with tip on it. Then I tipped in cash and the servers on more than one occassion still charged my room key! Yikes.