I think that should work... I have 4 Samsung M2 SSD in my QNAP TVS-1282T3 as cache...
BUT: the exact type is crucial for compatibility! So please check the QNAP homepage, there is a chart for each compatible type.
Good luck

The way I see it, this should work, yes. They give as additional recommendation min. 4Gb Ram for 1TB SSD cache, but the product already has 8 by default.