It’s too early to think about styling. Let the tree grow and gain energy. When temperatures are above freezing in your area, move the tree outside into the sun. Let it grow, and maybe introduce some bends with wire if you want a curvier trunk and branches, but don’t prune anything for the first full growing season.
To give you a heads up, you’ll need to water more often in direct sunlight. Also, Ficus microcarpa is a fast grower, so watch out for wire “biting” into the bark as the trunk and branches thicken. Remove and reapply wire as necessary.
Once the tree has gown out for full summer season and into the early fall, prune it back hard and bring it inside before the first frost, and keep it in a warm, sunny spot. Growing lamps are good if you want to go high tech, but a south-facing window will keep the tree going through winter, until the last frost in the spring. Then repeat that cycle, pruning once per year in the fall, until you have a thick trunk with lots of branches to style.
Whether the trunk is “thick enough” is up to you. It’s a mater of taste. However, if the tree recently had many dead branches, it’s likely weakened, and it will benefit the tree to allow it to grow unrestrained all summer. At least allow it one season to grow without interference.
Edit: To clarify, I prune in the fall so that my trees in development actually fit inside my house. Once your tree is mature and refined, you’ll be pinching off new shoots continually throughout the summer, and occasionally in winter, too.
