thank you for sharing your question with the Wefugees Community!
Generally speaking, a "Fiktionsbescheinigung" says that the "Ausländerbehörde" is still in the process of examining your residence permit. The problem with the Fiktionsbescheinigung is that it gives you the right to stay in Germany for now but that it is only temporary and can end any time when the Ausländerbehörde is finished examining your case.
Therefore I would highly recommend that you go to a free counselling centre or a lawyer (maybe you have one already) as soon as possible - to check all the possibilities you and your family have to stay in Germany. Sometimes there are more than just one options and a good counselling centre or a lawyer can help you with it. They can also help you with the question if getting a better paid job NOW will help your family to stay in Germany. Generally speaking I would probably say yes but I don´t know all the details about your case and for example don´t know exactly if you fulfill all the other requirements to receive a residence permit. Via this websites you can find free and trustworthy counselling centres:
I hope this answer was helpful for you. If you have more questions please don´t hesitate asking the Community again!
All the best
Note: Please keep in mind that we can´t provide qualified legal advice via the internet and that any information given can´t replace such legal advice.