Is Botox and Restylane Safe for Patient Under Lupus Medication?

The risk of poor immunity leading to infection is the main issue with Lupus patients on the usual drugs.
You should always remind your physician about your condition and insist on a very strict aseptic technique. For example, usually we clean the skin with alcohol wipes, for someone like you I would use Betadine to clean it even more.
Regards.

I personally have a patient with history of lupus (SLE) that is in remission and has done fine with years with Botox, Evolence and hyaluronic acid fillers such as Restylane or Juvederm. Having autoimmune conditions such as lupus is not an absolute contradication for botulinum toxin and filler injections, particularly if the condition is in remission. The key is to refrain from injectables when the autoimmune disorder is not stable. The safety margin for aesthetic injections such as Botox or fillers increases if the lupus patient is on antimalarial medication such as hydroxychloroquine and there has not been any autoimmune flare (e.g. arthritis) in the past 12 months.

The risk is not with Botox or Restylane in a patient such as yourself.
The risk lies with the medications you are taking (Prednisone and Azathioprine) -- both these medications are powerful immunosupressants. They increase the risk of infections. So while the risk of infection from the needle pricks is very small in people with a normal immune profile -- your risk would be higher and meticulous skin preparation should be used.
Other than this consideration, you should not incur other increased risks.