It depends a lot on what sort of cushions and what sort of curtains, but generally you get what you pay for.
Upholstery fabrics which are going to be sat on need good resistance to abrasion and to pilling but cushions that are purely decorative don't need to be so robust.
Measured in Martindale units
https://en.wikipedia.org/wiki/Martindale_(unit)https://www.jover.es/en/news/201-abrasion-resistance-textilesFabrics for window curtains need to have good UV light resistance but that's less important than for internal curtains that are not exposed to sunlight. Usually a good quality lining is sufficient.
Any fabric used for upholstery in public places - and recommended for private use - must be fire retardant.
My daughter makes curtains professionally, and does some upholstery, and she
won't compromise on that one.
If you are using a printed fabric ensure that the print is on-grain widthways. You have to cut with the design and if it's off curtains won't hang properly.