"comparable capability" refers to the text performance only, to keep it simple (the hardest part of making GPT-4 is the language model anyway). To be comparable the performance should be equal or extremely close across a wide range of benchmarks (e.g. MMLU, HumanEval, WinoGrande) and tests (e.g. SAT). It should also have at least 8k context length (chosen since GPT-4 has 8k and 32k context length versions).

Of course, to qualify as YES, the group that develops a competitor must publicly announce that they trained an LLM with the benchmark results.