I will refer you again to a very important paper: Why Neurons Have Thousands Of Synapses, A Theory Of Sequence Memory In Neocortex. Specifically, that paper states:
This can be calculated as the product of the expected duty cycle of an individual neuron (cells per column/column sparsity) times the number of patterns each neuron can recognize on its basal dendrites. For example, a network where 2% of the columns are active, each column has 32 cells, and each cell recognizes 200 patterns on its basal dendrites, can store approximately 320,000 transitions ((32/0.02)*200). The capacity scales linearly with the number of cells per column and the number of patterns recognized by the basal synapses of each neuron.