Yes - all code for differentiable programming in Swift has been upstreamed to main (done for a few months now), where development continues.
About Swift for TensorFlow: S4TF is switching to build using Swift.org - Download Swift toolchains instead of custom ones from tensorflow branch. This effort is in progress and is almost done! (See recent tensorflow/swift-apis PRs about "migrating to standard/stock toolchains".)
This means "de-forking Swift for TensorFlow" for good, which should allow Swift for TensorFlow developers and users to leverage all the tooling and infra for apple/swift:main branch, like Swift.org - Download Swift toolchains and ci.swift.org artifacts (continuous assert snapshots) for all supported platforms. 