To gain 1 pound every day, you need around 21000 excess calories. So if you consume an excess of 500k calories daily, we can calculate the weight gain by:
weight gain = (30 days)(500,000 calories/day) รท (21,000 calories/1lb)
weight gain = 71 lbs
In consuming an excess of 500k calories daily, you will gain 71 lbs in a month.