The perovskite rare-earth titanates are model Mott insulators with magnetic ground states that are sensitive to structural distortions. These distortions couple strongly to the orbital degrees of freedom and, in principle, it should be possible to tune the superexchange and to manipulate the Curie temperature ($T_C$) with strain. We investigate the representative system (Y,La,Ca)TiO$_3$, which exhibits low crystallographic symmetry and no structural instabilities. From magnetic susceptibility measurements of $T_C$, we demonstrate direct, reversible and continuous control of ferromagnetism by influencing the TiO$_6$ octahedral tilts and rotations with uniaxial strain. The relative change in $T_C$ as a function of strain is well described by textit{ab initio} calculations, which provides detailed understanding of the complex interactions among structural, orbital and magnetic properties in these compounds. The demonstrated manipulation of octahedral distortions opens up far-reaching possibilities for investigations of electron-lattice coupling, competing ground states and magnetic quantum phase transitions in a wide range of quantum materials.
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