or are you referring to the manager here are the marketing manager
Obviously, signature campaign is a form of marketing, calling it as a marketing manager is the same for campaign manager, people are just used to call the latter.
While it's not necessary to hire such manager since anyone here can handle/manage a campaign, but dont expect you will get the same results. If op is too busy handling other matter outside of this forum then hiring one is a huge help, but to make sure money should be considered.
I think there have been so many contributions to how op can promote his casino if he has in mind to take the casino to a new level where gamblers can easily go and play bet without much fear of losing fund. Advertising your casino here will give more views and increase traffic to the gambling site and more gamblers will tend to use the Casino and in case of any issues, it can easily be resolved unless the casino decides not to clear customers complains.
There are good numbers of gamblers who regularly visit Bitcointalk on a daily basis to find good and reputable gambling platform to use and if your casino is among the reputable ones, there will be more gamblers visiting your casino.