Lupus. Does it cause arthritis-like finger deformities over time?

Not really. Lupus can cause joint pain. If you have lupus, you more likely have another arthritis problem more common than sle.
Yes It Can. There are a variety of types of joint involvement that people with lupus can get. It is uncertain what you mean when you state "arthritis-like" finger deformities. People with lupus are normal people who happen to have lupus. Thus they can get arthritis which can occur with lupus but they can also get joint involvement that is not related to lupus. You need an evaluation to answer this.