Affidavit of support is required. But sometimes NAIA immigration officer are not asking it. Just to be sure, send the original copy with stamp of Phil. Embassy-Qatar.

If you have flat/house contract give them a copy as another proof.
Hopefully, hindi sila ma-offload sa plane by the crocodiles at the NAIA immigration, which is common modus-operandi ng mga tao sa NAIA para sa mga first time traveller going Middle East.