How to specify steps_per_epoch and validation steps on infinite dataset?
This can be explained only if you specify the total number of samples in your entire data set. The 200 Gb file size might be because of a large number of features for each sample in the dataset. The is how steps_per_epoch and  validation_steps work.
The training generator will yield steps_per_epoch batches.
When the epoch ends, the validation generator will yield validation_steps batches.
so usually the ball-park value for a decent number of batches in training is 75.  and that of validation is 25. if youre having a train to validation split of 3:1 for a 1000 sample data set. so that each of train and validation set batches will have 10 samples each.