This is pulled from an IDEA article. The link is posted below, if you want to read the whole piece:
How much you can expect to make from teaching Pilates depends on your qualifications, your ability to retain clients, your arrangement with your employer (unless you work on your own) and the area where you live (Schroeder 2009). Keep in mind the following:
The higher the level of your training, the higher your hourly rate of pay will be.
The more specialization you offer, the more money you can charge per hour.
The more you retain your clients, the higher your value is as an employee.
The more benefits an employer offers, the lower your hourly pay is likely to be.
The 2008 IDEA Fitness Industry Compensation Survey found that the mean hourly rate for Pilates instructors in the United States was $32.25, with professionals in the Northeast and West averaging more than that ($40.38 and $36.02, respectively) and those in the South and North Central region averaging less ($28.58 and $24.61, respectively). For-profit facilities paid more than nonprofits.
Fewer than half of the facilities included in the survey hired Pilates instructors as employees; however, in 33% of cases, they were eligible for educational funds. If the club or facility where you work includes educational opportunities as part of your compensation package, these are added value; likewise with management or career-enhancement options within the company.
as Ariadne indicated, there can be quite a range. It also depends on whether it is private instruction with apparatus or taught in a group setting. At a local club, Pilates instructors are paid $25 per class.