The blazar TXS 0506+056 underwent a major gamma-ray flare in 2017, lasting more than a year. The continuous gamma-ray data available during the flare and the long duration of the flare are advantageous to study the neutrino emission potential of the source, assuming correlation between the observed gamma flux and the neutrino flux. KM3NeT-ARCA is an upcoming km^3 Cherenkov Telescope in the Mediterranean Sea, capable of studying astrophysical point-sources of neutrinos with a median angular resolution of upto 0.1 deg .
In this contribution, the sensitivity and discovery potential of the KM3NeT-ARCA detector to TXS 0506+056 are reported as a function of time during its flare. For a gamma-ray flare with the same luminosity as that of 2017-18, we find that KM3NeT-ARCA would need six months or less to detect the source, depending on the model assumed. Assuming a constant average flux, the source would be detectable with a significance > 5σ in 2 years of observation.