  Alterations of the gravity Lagrangian introduced in modified torsion gravity
theories---also referred to as $f(T)$ gravity---allows for an accelerated
expansion in a matter dominated Universe. In this framework, the cosmic speed
up is driven by an effective `torsion fluid'. Besides the background evolution
of the Universe, structure formation is also modified because of a time
dependent effective gravitational constant. Here, we investigate the imprints
of $f(T)$ gravity on galaxy clustering and weak gravitational lensing to the
aim of understanding whether future galaxy surveys could constrain torsion
gravity and discriminate amongst it and standard general relativity.
Specifically, we compute Fisher matrix forecasts for two viable $f(T)$ models
to both infer the accuracy on the measurement of the model parameters and
evaluate the power that a combined clustering and shear analysis will have as a
tool for model selection. We find that with such a combination of probes it
will indeed be possible to tightly constrain $f(T)$ model parameters. Moreover,
the Occam's razor provided by the Bayes factor will allow us to confirm an
$f(T)$ power-law extension of the concordance $\Lambda{\rm CDM}$ model, were a
value larger than 0.02 of its power-law slope measured, whereas in $\Lambda{\rm
CDM}$ it is exactly 0.
