Can be used similiar to　あなた{達・ら・etc} and is more polite.

I asked a Japanese English teacher if I could use 医者がた. His response was no. His understanding of the use of がた was that it tends to be used for groups of people who are generally expected to be older than a particular group of people. For example, teachers are generally thought of as older than students so you can use 先生がた. Senior students are generally older than junior students so you can use 先輩がた. Parents are older than children so you can use 親がた. あなたがた is commonly used although it doesn't fit this rule. However, he said that there is no guarantee that a doctor or dentist will be older than their patient so he said they wouldn't use this construction for these groups of people. Any thoughts anyone?

The nouns that don't take がた are typically:
※ First or second-person pronouns like 私, 君, 僕, 俺.
※ Close, familiar, or intimate referents—people you already have a casual relationship with.
※ Words that don't imply a social group with recognised status.

Examples:
(君/きみ) — 君たち✅ vs 君がた❌
(彼女) — 彼女たち✅ vs 彼女がた❌
(僕) — 僕たち✅ vs 僕がた❌
(私) — 私たち✅ vs 私がた❌
(学生) — 学生たち✅ vs 学生がた❌
(兄弟) — 兄弟たち✅ vs 兄弟がた❌
(子供) — 子供たち✅ vs 子供がた❌

※ ～がた isn't a productive pattern; the nouns it works with are very limited, so it's safest not to use it if you're unsure.
※ 私の先生がた❌ sounds off. Adding a possessive like 私の makes it sound like you "own" the group, which clashes with the social/polite nuance がた carries.
In practice, whenever you want to use がた with a possessive, it usually sounds unnatural.