If you are looking to submit a marketing proposal to Gate.io, you should contact their business team at business@gate.io. Make sure to include a detailed description of your proposal, including the intended goals and objectives, target audience, timeline, budget, and any other relevant information. Additionally, you should provide examples of any past marketing activities you have been involved in. By providing this information, you can ensure that the Gate.io team has a clear understanding of your proposal, allowing them to make an informed decision.