King brought in $1.33 billion in revenue from its "Candy Crush Saga" property alone in calendar year 2014. If we were to divide this out daily to 1 million children in Africa, that would be approximately $3.64 per child per day (($1.33billion/1million)/365days).
The cost to feed a child in Africa seems to vary wildly from source to source, searching yielded results from $1 down to $0.19 depending on the charity. A 2009 study found that African schoolchildren across multiple countries were fed on the equivalent of $40/year (standardized at feeding a 700 Calorie meal 200 days of the year), which works out to $0.20 per day ($40/200days). Since this is only one meal of the day, we can assume it would cost $0.60 to feed a child al three meals. Thus the $1 estimate in your source is higher than expected (but could cover more varied food and administrative costs).
Either way, the above translating King's revenue for a million children ($3.64 per day) is greater than that calculated costs of a full meal by a factor of 6. So it is within reason that King's yearly revenue could feed a million Africa yearly, if not more.