I ( an experimentalist) will wade in where angels ( theorists) fear to tread :).
There exists this great in length report by CMS where you will see in the introduction part of the motivation for the experiment as :
Various alternatives to the Standard Model invoke new symmetries,
new forces or constituents. Furthermore, there are high hopes for discoveries that could pave the way toward a unified theory. These discoveries could take the form of supersymmetry or extra dimensions, the latter often requiring modification of gravity at the TeV scale.
So experimentalist have been lured to look for extra dimensions, one of the possible marks of string theory, as "predicted" by various phenomenological models.
If nothing new/unexpected like this is found, it will not preclude that string theories are waiting for us as the theory of everything in the future.
If a signal of extra dimensions is found in the data, then string theorists will be singing a different, not so cautious song.