The Illuminati probably does not control all of the money in the entertainment industry. Although it remains a popular conspiracy theory, there is no evidence to support it and considerable evidence debunking it.
Although the Order of the Illuminati did exist as a secret society, it was not a shadowy organization out to run the world. It was founded in 1776 to fight against superstition and abuses of power by the state, among other lofty goals. However, it was outlawed with the support of the Roman Catholic Church. As of 2015, several other occult or secret organizations have used the name as a recruiting effort, but they are generally fairly transparent and well-known.
The Illuminati conspiracy theory stems largely from supposed secret symbols used in music videos and movies. However, these are common symbols in a variety of art forms. A commonly cited example is an eye in a triangle, but that is so widely used that it is found on U.S. paper money. Some savvy entertainers have also realized that including these supposedly secret symbols in their art draws a great deal of attention on websites and forums. This helps advertise the art to a wider audience and increases views, making it an easy marketing strategy.