SuperData Research estimates that the gaming industry will earn around $74 billion in 2015. This includes PC, console, and mobile gaming. Other forms of "playable media" are included as well.
The size of the gaming market is approximately three times of what it was a decade ago. With entertainment becoming increasingly interactive and the lines between mediums blurring, there has been massive room for expansion in the industry. One of the most significant factors in the increase is the rise of mobile gaming over the past few years. Mobile games by themselves make up over $22 billion of the $74 billion figure.
Physical media is the largest source of revenue, but it seems digital media will overtake it in a matter of years.
For comparison, the film industry earned around $30 billion in 2013.