The basic build looks fine. The “H” signifier after the CPU indicates that it has a higher core-count than the standard “U” CPUs, so that’s great. Also a GF1070 is what I play with at 2560x1440 ultra detail, and it runs just fine. Mind you, you’ll want to upgrade the RAM and hard drive at some point. Fortunately, those are both very easy upgrades.
Note, that many Dell laptops (Dell owns Alienware) have had issues with not accepting all brands of DDR4, so if/when you upgrade the RAM, be certain to check compatibility first. The brand I’ve had the best luck with on the high-end Dell laptops I’ve deployed at my company has been Corsair, whereas with HyperX they won’t even boot.
Here are the RAM and SSD options that I’d recommend if you do go with that laptop:
https://www.amazon.com/Samsung-970-EVO-1TB-MZ-V7E1T0BW (they also have a Pro line that’s faster and more expensive, but but the Evo series has always worked well for me)
Also, a 17" laptop will be heavy and huge as they are intended as “desktop replacement” style laptops. If you will chiefly be doing all of your PC gaming from a fixed location, a desktop-based system will give more bang for the buck. Mind you, you’d then also need to buy an external monitor, so that could eat into the cost-savings of buying a desktop unless you just hook it up to the TV in the interrim.