Ficus just stops growing. Basically, each process in living tissue has an optimal operating temperature. For humans, all processes are 'finetuned' to be run at about 37 degrees celcius, our ody temperature. Ficus typically are found in area's with 20+ celcius temperatures, which is why they prefer higher temps: The proteins in their cells work best at temperatures of 20-30C. Lower temperatures have less of an effect then higher: At low temperatures the proteins still workl, ut slower. At higher temps, a lot of proteins may stop working.
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In concluding summary: no. Just giving more light will not help, as it is not just phiotosynthesis which slows down. Also root-growth (Which for all plants stops at about 10C in the rootballs) cell-divisions, repairs etc. slow down considerably with lower temperatures.
However, IF you just want to kep the plant alive, you may consider keeping it on the dry side outside for longer. Just keep in mind that for allmost all ficus species frost is dreadfully harmfull, even just a nights worth of it..