I am not an expert but an interested party. I would think you would have the heeby jeebies with that large of an infected plant. I would isolate it from any other plants you might have. I think pruning it would be your best option and then wiping every itty bitty stem off with alcohol on a q-tip. Could you put it outside? Don't prune until you have gotten advice from an expert. I think it will all come back if it is not too sick.

I would be very nervous about cutting back a big plant like that to just stems. I am no expert on ficus, but would suggest treating the plant without pruning first to see what kind of results you get. There are systemic insectides that are applied to the soil which will travel throughout the entire plant. Also, scales are very susceptible to oil sprays, so a horticultural oil treatment might help. You will want to move the plant outside or cover up your furniture and carpet before spraying. If you can get your scale identified, there may be a parasitic wasp that will kill it also. Parasites are pretty host specific, so you need to have this right first. Also, don't expect a quick response to biological control. It is likely to take a number of months.