“The Greek military is about 40-50% of the size of Turkey’s. It is tough to declare war against a much larger opponent.”
Worse odds have been overcome, especially by a determined defender. Turkey has to defend a lot of frontier areas facing other potential hostile neighbors. Turkey is also engaged in combat operations inside Syria.
If Europe doesn’t want an influx of a million more migrants, then they ought to send their own forces to help stop the invasion, and not expect Greece to be able to do it alone.
Worse odds have been over come in the past by the GREEKS.