How many images are generated when ImageDataGenerator is used, and when data augmentation is included as a part of the model?
In one epoch - It's the number of images in your Directory or the DataFrame
 In case of a custom Generator. It will be batch_size * steps_per_epoch
You may check this with any of these approaches -

Check the shape of prediction on train model.predict(traindata).shape
Save the images into a dir by using save_to_dir='/content/train_data'
Write a callback for batch_end
Get the steps_per_epoch in the training print statement i.e.
125/125 [==============================] - 50s 392ms/step - loss: 0.6637 - accuracy: 0.6000