If queen die in the hive, bees raise new queens. They will have queen cells.
1) If you give queen cells from another hive, they smell it often strange and they destroy the cell. Cell can also been violated.
2) If they have already their own new queen, they destroy other queen cells and queens. I can find it out when you give larvas into hive. If they raise queen cells, they are without queen. If nothing happens, they already have a queen.
It takes about 3 week (minimum) to raise a new queen and to have it fertilized. If you have much rainy days, fertilizing will be moved.
The hive gather very well honey without brood and without queen.
If hive have no queen, often it can be seen from their behaviour. They ventilate and they have their odor gland open. If you let them to smell another's queens taste, they start to ventilate eagerly. If they have already own queen, they attach against the stranger. Of course queen must bee in the cage.
Put young larva frame into the hive and see what happens.