None.
A gallon is a measure of volume whereas a cubic foot per second is a measure of flow-rate. The two measure different things and, according to the basic rules of dimensional analysis, conversion from one measure to the other is not valid.
7.42 cubic feet/second = 55.51 gallons/second [US].
There are 7.48 gallons in a cubic foot
One cubic foot of water is 7.4805 gallons.
There are 7.48052 US gallons per cubic foot.
There are approximately 7.48 gallons in a cubic foot.
7.48052 US gallons per cubic foot.
There are 7.481 gallons in one cubic foot.
One cubic foot is 7.48052 US Gallons (6.22883 UK Gallons)
My guess would be 7.48 gallons since that is how many gallons of water is in a cubic foot
1 cusec, or 1 cubic foot per second, would be 7.48 gallons per second.
One cubic foot = about 6.229 Imperial gallons.
7.481 gallons equal one cubic foot.