If you have incandescent lighting, that willl add warm tones and accentuate the purple. I had to change the bulbs in my dining room and powder room to canccel out purple in blue and grey walls. You may be fighting an uphiill battle though because the golden color of the brick behind it is going to bring out the purple. I think you are going to wind up changing the wall color (not a huge advocate off painting or whitewashing brick, but sometimes.....), changing the sofa, or deciding to work with the color you see.

Your room is lovely; it's unfortunate that some people get satisfaction from being rude - must make them feel better about themselves somehow. When you put the sample against the couch are they different or the same? Or did you not actually have a sample or just the pic of it. If you don't have a sample, I'd order one and see if they are the same. The color is lovely; I personally think it is much more interesting and livable than a darker gray would be, but that's me, not you. It looks great in your space. Will the store take it back if the fabric doesn't match the sample?

The couch actually looks gray on my monitor. Your walls are too yellowish (on my monitor), that could actually be from the type of bulb you have in the lamp back of the couch. Change that bulb to a daylight type bulb, and see if it makes a difference. If you have other lighting in that area, then make sure they have daylight bulbs too. I agree, the coffee table is not right, with your furniture. You could also use new end tables and side lamps, and a large rug in front of the couch. Your pillows on the couch, that you say are teal, are way too light colored and washed out. Replace them with something brighter.

I realize it isn't what you had in mind, but I think the "greige" sofa looks nice with your wall color. I also think the pillows it came with look nice in your space and like how the pattern (in your first picture) of the pillow relates to the object on the bottom right shelf behind the sofa. Sorry, I realize this probably doesn't help if it's not to your taste, but I think you have a nice start to a cozy basement. Also, I second the idea to keep your eye out on Craigslist, FB, etc., for art. I snagged a couple of HUGE framed prints I love for $10 each on NextDoor a couple weeks ago. When I got home I looked them up online by the artist signature and found they were almost $300 each to purchase framed. You can also try home stores (such as Home Goods and At Home) for mass produced art at reasonable prices.