Accepting CFO's letter is purely discretional. In other words, the adjudicator can decide whether to take CFO's letter as a proof on ability-to-pay. The case can be denied even with CFO's letter.
According to Yate's memo, the primary sources of info to prove ABility-to-pay are the following three: 1. Federal Tax return; 2. Audited finiancial statements; 3. Annual report. If any one of abovementioned three documents shows enough net income to meet ability-to-pay requirements, your I-140 will get approved.
Another approach is to submit your W-2s. If you got paid proffered wage (the wage stated on your labor certificate) from the priority date, you will get approved even if you don't submit the abovementioned documents.
I hope this helps.