Pronunciation: [ɡˈe͡ɪnste͡ɪ] (IPA)
Correct spelling for the English word "gainstay" is [ɡˈe͡ɪnste͡ɪ], [ɡˈeɪnsteɪ], [ɡ_ˈeɪ_n_s_t_eɪ] (IPA phonetic alphabet).