How is oscillation condition fulfilled in this oscillator circuit?
You are failing to take into account the fact that the capacitors are reactive.

Ignoring the coil, the load seen by the collector is this \$-j 27\Omega\$ in series with the parallel combination of \$-j 27\Omega\$ and \$25 \Omega\$.

That appears to the collector as a \$129 \Omega\$ resistor in parallel with a cap having a reactance of \$-j 44 \Omega\$.  Cancel that reactance with the right inductive reactance, and the collector sees just the \$129 \Omega\$, for a gain of around 5 -- which is (A), not unreasonable for an oscillator (you want lots of excess gain on startup), and (B) probably a significant overestimate, because it's not taking the transistor's losses into account.